Do you know what his kidney values are now? What you describe is very typical - many dogs in kidney failure won't eat the prescription kidney food - it's not very palatable. That is why the yahoo k9kidneydiet group started - many people have had success with home prepared kidney diets. At this point, it's important that he eats. Here are some lower phosphorus items that you can offer:
Green tripe
Vanilla wafers (these are human cookies) - (my CRF Cavalier lived on vanilla wafers for about ten days once - this is a low phosphorus item that they will often eat, esp. because it seems like a treat and is sweet)
Egg whites - very good source of high quality protein, very low phosphorus - I just put them in the microwave and poached them. Egg yolk is very high in phosphorus so just feed the whites
Meat baby food - can't feed long term but can use for a dog who is not eating at all
Boiled chicken thigh mixed with farina or cream of wheat. (White rice is a high phosphorus grain, most of us use glutinous rice, similar to sushi rice - it is sticky) Chicken thigh is lower in phosphorus than chicken breast and is higher in fat so not good for any dog prone to pancreatitis but good for kidney failure dog who can tolerate fats.
Do you have phosphorus binder which is given right after a meal? This helps the phosphorus move through the intestines without the kidneys having to remove this waste. Binders are either aluminum hydoxide or calcium carbonate (not as strong as the alum hydroxide).
If you home feed, you will have to add calcium to balance the meals - but you don't have to learn about that right away. Right now it's just important that he eats.
Have you talked to the vet about giving daily subq fluids at home? As I mentioned before, this for many has been the key to giving a good quality life and extending length of life considerably (years).
Is he taking antibiotics now? Those can cause loss of appetite in addition to the kidney failure (uremia/azotemia) causing loss of appetite. What are all the meds he is taking?
I wish I lived near you and could help you. Some good links:
http://www.dogaware.com/kidney.html#diet
Recipes on homemade diets for renal problems can be found at this link:
http://www.b-naturals.com/newsletter/kidney-diet/
Here is link to the K9Kidney Yahoo Group:
http://groups.yahoo.com/group/K9KidneyDiet/
Thinking of you,
Pat