I'm sorry Pepper is not doing well right now, but I'm encouraged by the fact that you are able to get as much food in her as you are. Good for you! The cure for hepatic lipadosis is food. It can take quite a while - several months sometimes, for the problem to resolve, but diligent owners like yourself often have success with getting their cats back on the right road. It is important that she is passing stool. That way you know things are functioning and she is getting enough nutrition to have some waste. The best idea I have for you on short term basis is to go out and buy Pepper a litter box of her own and confine her to one room of your home with food, water and the box. She should have at least ONE bowel movement in 24 hours. Also, it will better enable you to monitor exactly what she is taking in. You might get a few jars of Gerber Baby Meat - plain pureed chicken or turkey and put about 1/4 of a jar out for her to see if she may show some interest in eating on her own in addition to what you are giving her. Getting her eating on her own is the biggest key to winning this battle. If she is constipated (which I doubt-given the amount of liquids she is getting), you can add some canned pumpkin (not pumpkin pie filling) or pureed Gerber Baby Squash to her canned food. This will help get her moving.
It sounds like you are definitely on the right track. I think isolating her is the only way you'll be able to monitor what exactly is going on with her output for a while. You can let her out a few times a day once you see her going. Please let me know if I can do anything else for you!