I just switched Bailey to the homemade low protein diet from the University of Tennessee website:
Portosystemic Shunts FAQ (look for the link on the lower left hand side to see the recipe)
My little guy was a bit of a picky eater and he loves this stuff. He is 3lbs 11 oz and when I make this up it will last about 5 days or so. I feed him almost 2 oz of this twice a day. Our vet suggested a low protein diet after high liver enzymes from a blood test. We told him about this diet and he liked it. I've been thinking about starting a thread to see if anyone else on YT uses this diet. Best of luck with Benji.