The website will have 1) His history/ current situation/ goal. 2) A set monetary goal and its uses - and an online counter. 3)Donation page and download of free content (art by him or coupons from near by establishments. What would move you to support and donate? An awesome website? A great video? Really fun perks?
What is your goal with this?
To change his situation? To raise funds? To get a cut of the donations? To increase awareness to homelessness?
Admittedly, I don't know all the details about your venture, but I see a lot of holes that need to be closed before I can answer what would inspire me to give him funds.
I'd be really curious to talk about this more to understand.