Being honest i think your best bet is finding help through a law firm or organization specific for cases such as your pals in his state. I couldn't imagine too many people would be willing to donate/ send monies to a man in prison when his case is just one of many and lets face it people do not part with their dollars easily and specifically many do not trust prisoners in the first instance. Even i would not send funds in all honesty and i am a born giver.
My advice, do a little research as to what help is available in his state. More than likely he should have some info if he has been inside long enough, they usually do know who does what in their state after sharing in conversations with other prisoners and reading the papers, etc. Sometimes i think we need to put our money where our mouth is too. Although i know many disagree with me on that one.