Found kitten in garage, need some help/advice please!

Ok, so I have perused the site and many others for help with this and have not found the exact situation I face, so maybe I can get some assistance.  

Tonight around 8pm, we were sitting on our deck eating dinner and we heard meowing, sounded distressed, we thought from the alley between our fence and garage, but turned out nothing was there.  We thought there was no way a cat could have gotten in our garage because we hadn't had it opened in a few days, and surely it would not have survided in 120 degree stuffy garage for several days with no food right?  Wrong.  We went in and saw a flash of white run behind some boxes.  So we immediately got some milk in a bowl and the girlfriend ran to the store to get a bag of food and some fancy feast kitten food.  I stayed back and tried to locate it in the mess that is our garage, I tracked it down a couple times and could not catch it, getting close, of course it hissed at me and ran into another unreachable spot.  I have never had a cat, I have lived with roomates that did though, older cats, but from what I can tell from looking at aging charts, this kitten looks to maybe be around 8-12 weeks old at tops.  I may be misjudging from its size, because as I said, we had not had the garage open in at least 3 days, and it is likely starving/dehydrated.  So we set some food, water and milk out in an open area and we just patiently waited for about an hour and nothing, it just sat staring at the food from under a dresser.  So, we decided it was probably scared and we should just exit the garage for a while and let it eat.  Pass by another 30 minutes out of the garage, I look in through the window and the poor thing has drank about 3/4 of the milk, maybe some of the water, couldn't tell, and had not touched the whitefish food.  We don't just want to leave the garage open for it to run free because from what I have read, the kitten likely will not survive on its own at this age as a feral.  We have several ferals roaming the neighborhood, maybe 3, so it could be one of their kittens, but I don't think I really would feel right about just setting it loose like that.  I checked all the local websites where people post lost pet notices and have found nothing.  We had been talking about adopting a cat recently anyway, so we are heavily debating adopting it, we know about taking to the vet to update its shots and make sure the poor thing is ok as soon as we catch it, but there lies the problem, we can't catch it.    It's a beautiful cat too, white as snow every bit, it's eyes are already yellow, he/she is filthy though right now, being stuck in that garage so long.  So I am worried about possible heat stroke/heat damage, and how do we go about catching it/getting it to warm up to us??

Sorry for the wall of text, wanted to include everything I could think of.

If the garage is hot, don't leave him in there. Open the door and let him out and continue to leave food and water for him by the garage. He's survived this long as a feral, so he has some basic survival skills. Then rent, borrow or buy a humane trap. If he's ill, take him directly to a vet while he's in the trap. You could also try to throw a towel or blanket over him and scoop him into a pet carrier. It will take some time to build trust with him. It's great that you're helping this kitty and you'll get some great advice here. I'm just worrying about leaving him in the hot garage for too long if you can't catch him.

Welcome to TCS and Bless you both for looking out for that defenseless kitten   It sounds like a very beautiful kitten and although probably shyer than a kitten raised among humans, will make a wonderful addition to your family.  Apparently, there must be an area in the garage where the temperature stays tolerable and if it were me, I would set a trap for it in the garage. 

It is rare for a feral kitten to be born into a single litter and if it gets out of the garage, while searching for its feral family, faces many perils, including hawks, owls, cars, dogs, evil people, etc. Also, you risk the kitten getting away for good, and, if that happens, it will reproduce many more kittens, most who will not survive but rather, be born into a short life of hardship and suffering, until death comes, often as its only friend in its brief, sad life. 

Since the kitten is feral, be expected to hear lots of terrified screams and protests when it first gets captured. Since cats are more often prey than predator, their instincts tell them that humans intend to eat them. And their mothers often give subsonic growls when they see people, thus reinforcing the notion that we are the devil himself    The key is to keep calm and reassuring, both to kitten and yourself. I find that talking to the wild cats help me keep my emotions in check - cats pick up on the very subtle changes in our respirations, perspirations, etc.. No matter what the kitten may think, you are actually a savior and hero!!!

HINTS: BE PREPARED for successful capture - prior to trapping, have a crate, carrier,  or a tall, roomy cardboard box for the kitten to "cave up" in. also, put in a small litter box in the corner ( i use the heavy plastic trays that some meat, esp pork chops, come in). I recommend having a soft nest inside as well, using rags, towels, add a stuffed toy for comfort. Place the cave inside another room, such as a bathroom or bedroom, so if the kitten gets out, it isnt free-roaming. Rather than feeling trapped, confined areas give a small kitten comfort. Also, it's much easier to get acquainted. I also try bottle-feeding them (even if they are weaned) and I use the corner of a damp washcloth to "groom" them, using tiny strokes to imitate a mama-kitty's licks followed by "licks" with a fine-toothed comb. If there are fleas, you can use warm salt water on the fleas to slow them down and then de-flea the kitten manually. Probably, you will initially need to wrap the kitten in a "burrito" using a large towel or stout cloth (remember, those teeth and nails are sharp - handling a panic kitten is like handling a cactus on meth). When trapping, be close by and immediately cover the trap with a towel or blanket so the kitten calms down. Best of luck on this stage of the game.

Instead of milk, you could try giving it some "kitten glop" (I call it formula", using the homemade recipe from kitten-rescue.com. I use canned goat milk and dilute it by another 1/3 with water to prevent diarrhea. Goat milk lacks the lactose of cow's milk and is cheaper and more natural than the whey & nonfat milk found in the commercially prepared kitten formulas, including KMR. Diarrhea can cause or enhance dehydration. Also, you could add some unflavored pedialyte (store brand is fine) to the water, to help the kitten rebalance its electrolytes.

Please keep us updated on how it goes - and remember, we LOVE pics 

A second to not putting milk out as many cats are lactose intolerant and it could cause painful gas and tummy upset.  We have learned we must attach the dish we put food for bait in to the back of the live trap.  Cats can reach in and pull the dish out without setting off the trap if you don't.  Probably an adult cat but you say there are some around and wildlife can do that too.  When we get a cat in a trap we just take the whole trap in to the Vet, saves having to put a feral into a carrier, which can terrify the feral and maybe you too.  Catching on a Sunday will wreck that idea though, unless you go to an Emergency Vet.  Good luck.

Or, with a kitten, we set up a room with box as described above and Vet later, months later, when the kitten is socialled all up.  This is feasible for you as you have no cats right now and don't have to worry about disease.  Except maybe rabies, which the chance of is remote where I live.