I have a 16 year old dog who's been on a home prepared kidney diet for 3 or 4 years now. Her rate of degeneration is very gradual, so I guess we're lucky.
The main thing is to keep levels of phosphorus & sodium as low as possible, and to feed smaller quantities of high quality protein. Mix the protein with rice and/or veg (steamed sweet potato is good). I feed my dog about 1/3 steamed chicken, 1/3 boiled white rice 1/3 sweet potato, all mashed up together.
I also use Burns hypoallergenic mixer as it has very low phosphorus/sodium - as low as the less palatable renal diets on sale. My dog enjoys this as a treat and, I guess, for the change in texture. It's also useful to have some in stock in case I ever run out of rice.
It used to be thought that 'kidney dogs' needed a low protein diet, but actually that's wrong; what they need is good quality protein which is easily digestible. Renal diets are quite often relatively high in fats (because this is a high quality easily digestible protein) but be careful that you don't overdo it as it can lead to pancreatitis. I give my dog a 'low fat day' (lean meat, no Burns kibble) twice a week just to keep things steady.
You may need to feed your dog smaller meals more often as they sometimes feel a bit sick if they eat too much. It's also common for kidney dogs to become very picky - this is again because of nausea. The trick is to find tasty flavours to tempt them when they feel bad. I find scrambled egg whites (not yolks - high phosphorus) & rice work with my dog if she's feeling off-colour. Readily availble fresh water is also a must - my dog has a water bowl in every room.
There's a
Yahoo group which goes into great detail about all the options and has recipes and so on. I found it a bit too intense, but there is some good information there, including how to balance calcium with phosphorus correctly which is very important.
Hope this helps.