You can get a recipe from a veterinary nutritionist and cook for him if you want.
The Hills L/D "dry" contains ethoxyquin, so I really wouldn't want to give it at all. The wet is quite a bit better. You could try Royal Canin Hepatic LS 14 kibble but it made my Yorkie extremely itchy. Royal Canin seems to do that to lots of Yorkies. You could also ask the vet if they think Natural Balance Vegetarian or something along those lines would be okay in this case.
There are supplements like Denosyl or Vetri DMG, milk thistle, lactulose, omega oils and vitamin E that are great for supporting the liver but I'm not sure if these things are given post surgery. You could ask your vet about them. If they say that you don't need to but that it could be of some benefit, I personally would do it (at least a couple of them depending on your particular dog).