First of all If he is into it, I would get him to juice as in the Gerson protocol. Get the Gerson book and follow it. Use only organic produce. Along with this I would begin full detox protocols such as colon cleansing, liver flushing, kidney cleansing, etc. Most neurological disorders are due to toxicity and lack of nutrition. Also look into magnetic clay baths and infra red sauna to help pull toxins.
What was your father's occupation? What kinds of exposures may he have had? Does he have mercury amalgams?
The key is to bring down his total toxic load and supply optimal nutrition. Then his body can heal.
Also you can utilize powerful guided imagery techniques which will focus your immune system. I recommend Dreamhealer's dvd to help with this.