I second the Slicing Pie concept (AKA Grunt Funding). Modify it so only a certain chunk of equity is in the pool and tie your milestones to extra points awarded. If you just want to see if the idea is for you, read Mike Moyer's summarization of his own Slicking Pie book called "Get Them Gators." It's just a few pages and contains all you need to decide if grunt funding is for you.
Note that most technical creatives tend to respond to these incentives positively only a few times (if at all) before your ROI for the prizes goes flat or even negative. There is a lot of literature out there about bonuses for developers, but author Dan Pink (author of Drive) puts it best in his books and TED talk: