Cat is old and has liver failure

I need ideas on how to adjust the current situation. I just recently found out my 17 yr old cat has liver failure. The vet said to keep him comfortable and make sure he has it a little easier. Since he is collecting fluid it can be a little more uncomfortable for him yo jump. His kitty litter box has been in the basment. I have a baby gate because my pomeranian lovers to venture in to his box and use the area as his own potty. I brought the kitty litter upstairs but the next day the whole living area smelt. I tried leaving a little hole.. lasted 2 days before dog found it. (squeezed under and around) I put a large box so he didnt have to jump so high, he jumped over it. I running out of ideas.Does anyone have any ideas? I just Want my kitty to confortable

I'm sorry to hear about your kitty's diagnosis.  I don't have any dogs so I've not had to deal with this situation, but I'm linking to a thread about this issue that may give you some ideas:

http://www.thecatsite.com/t/228079/keeping-dog-out-of-litter-box