Indoor/Outdoor cat to Indoor only, with a litterbox twist

So ten years ago I got my first cat, he was about two months old and I immediately paid to get him fixed. For about a year he was chronically weird about the litterbox: pooing in a closet, peeing in sinks bathtubs etc, and occasionally the box. I changed litter type a few times and he seemed to like old-fashioned clay. A new roommate moved in with his own female cat, and they both used the litterbox. Then I moved to a new apartment in a different city, and things still worked out. I had been a little worried since one of my roommates also had a male cat, but they both used it successfully. Then I moved to another apartment with different roommates and no other cat. He used the litterbox for a while, and then there was just a total breakdown. Peeing on couches, beds, basically every soft surface he could get a hold of until the final month I lived there I was just forced to move him into my room where he ruined my mattress and I lived with the smell of cat pee. All that time I tried everything I knew to do. Paid for professional cleaning of everything, kept the box scrupulously clean, tried new litter, went to the vet, all that. 

Finally I moved to a house in a different city and started letting him outside and eventually built him a cat door. I didn't like him going outside but he was happy. I was happy it didn't smell anymore and nothing was being ruined. However, I just was in a nasty breakup and had to move to a new apartment. My cat is still at the house with my ex, and in the interim I got a new male cat who does use the litterbox regularly. I was trying to secure a different apartment in a neighborhood where I would feel comfortable letting him out, but a) I'm a broke graduate student and b) ground floor access apartments aren't always the safest for people. So I'm tempted to try keeping him inside again. 

It was only recently that I was thinking through the problem and realized that he was pretty good about the litterbox when there was another cat around who used it. Maybe there's some sort of peer pressure thing? Regardless he's been fully indoor/outdoor now for around 3.5 years. So what to people think, is it possible to take an indoor/outdoor cat and make him a happy indoor-only one, especially given his history of making my living space smell like pee? What's the best way to do this if I try it? Is this foolhardy, and I should just try and find a different apartment and pay far more than I should? 

Yes, it is possible for a cat to go from being indoor/outdoor to indoor only.  Some cats make the change easier than others.   If your boy really wants to go outside, consider leash training him.  Many of our members walk their cats - check out the article below for some information.
[article="22521"]Cats On A Leash  [/article]
In terms of the box problem, it's understandable why you're concerned he might develop issues again.  No one wants a house that smells like cat pee - I speak from experience!  I've never heard of peer pressure encouraging cats to use the litter box - usually it's the reverse.  Many cat's don't like sharing the box and it's necessary to have multiple boxes.  The rule of thumb is one box per cat, plus one extra box.  There are many things you can try to get your cat back into using his box consistently.  Read the below for some ideas:
[article="32366"]How To Solve Litterbox Problems In Cats The Ultimate Guide  [/article][article="22302"]Litter Box Location Secrets  [/article][article="0"]Litter Box Maintenance  [/article][article="31189"]How To Choose The Right Cat Litter  [/article]
Many people also have great luck adding one of the Precious Cat Litter Attract products to the box:  http://preciouscat.com/product    The litter itself attracts cats to it by its texture and a special herbal additive.  It's a bit expensive but you don't have to use it forever, only until your cat is using the box as he should.  You can then start gradually switching over to regular litter.

One aspect that you should be aware of is that bringing two cats together in the same home might create territorial and dominance issues.  Although you might be lucky and your two cats get along right away, it's best not to count on that.  Read the following for some ideas on introducing cats:
[article="32680"]How To Successfully Introduce Cats The Ultimate Guide  [/article][article="29726"]Introducing Cats To Cats  [/article]
One final thing you might try is to introduce a calming agent into the picture.   This will help keep your kitties calmer during the introduction process.  These products are also useful in dealing with litter box issues caused by behavior problems.  Below are some of the ones our members have used.  Not every one works on all cats, and there are other products out there - these are just a few to give you an introduction.

1.  Feliway is available as a plug-in diffuser or spray.  It's based on a facial pheromone that cat's emit when they are feeling happy and content.  There is also a new formulation based on a pheromone that lactating mothers emit.  Here is the Feliway website:  http://www.feliway.com/us/#redirected.  Many members have found the best prices are at amazon.  It's important to note that one diffuser only covers 700 to 900 sq feet so you might need more than one diffuser.  

2.  Composure is a calming agent available in treat or liquid form.  http://www.vetriscience.com/index.php?l=product_detail&p=9008103030   Many of our members have very good luck with this.  

3.  Bach's Flower Remedies, in particular Rescue Remedy:  Many members report excellent results with these products.  http://www.bachcentre.com/centre/bfrani.htm

4.  Spirit Essences:  http://www.spiritessences.com/category-s/1876.htm   Another favorite with our members.

Good luck!  I hope it goes well.  

You're right that is weird. I hadn't even considered that point. He does seem like some crazy sort of exception though. The first time he lived with another cat, they totally shared a litter box. My roommate and I didn't even think about the rule since we didn't know it. It just seemed to work. But even with the second cat, later, the two litterboxes were right next to each other. Just as far as I can tell nothing he does makes any sense. I never used scented stuff; when we had non-clumping clay we cleaned once a week, dumping out the whole amount, otherwise it was about every other day; no physical health problems; doesn't have any mental issues, he's actually incredibly friendly; I never put the litterbox near food or water; I tried Feliway and it didn't seem to help; never put a covered litterbox facing a wall, and mostly just used open ones, etc. My thought about peer pressure was maybe it was sort of a training thing, he learned to do what the other cat did.

I actually just bought the Precious cat litter and am going to set it up for the current kitty, along with the OmniPaws self cleaning litterbox. I'll buy a second if it works for the current cat and try it with my old one. Just so he won't have any weird reactions to an old litterbox. I'll take the top off of it too if it helps him, and only put it back to clean. I'm going to have a month to move into the new apartment, I think (damn two months of rent). So I'm planning on getting a baby gate and introducing them slowly and taking him back to my ex's at night. I really want to make this work. The only things I haven't tried are the cat attract / litter, or the other three calming agents you suggested. I'm willing to try them all honestly. I got the new cat at the shelter specifically because he was super friendly with all the cats there. I think I'm doing everything right here. Just the last time he was indoor only it was awful and expensive which completely defeats the purpose of getting a cheaper apartment. 

Also I've read about adding literal dirt to the litter to remind him of the outside, thoughts on that?