How can we get sponsors for a Let's Play?

I'm pretty sure I put this in the right section, if I didn't then feel free to move it with my apologies

Anyway, hey everyone! My friend and I would like to do a 24 hour "Lets Play" stream where we pretty much spend 24 consecutive hours playing a video game, and streaming it live to an audience (with commentary, and a view of our faces, as well as the game. The whole deal). We also want it to be kind of like a fundraiser, sort of like a walk for breast cancer, or something of the sort, where all the proceeds from the sponsors go to a charitable organization like the American Red Cross or such.

Our question is, however, that we don't know where to look for these sponsors or where to stream our video. My friend claims that he has seen videos like these being done before, and for the same reasons that we are going to do it, he just doesn't remember where. So we would like to know where we can find sponsors for these videos, and where we should stream it to get the public's attention.

We don't have all the details about what game we will be playing (We won't be playing an over-played game like Super Mario 64) or what organization we will be donating to, because we would like to know the other details first.

Thank you for any insight on how we could get this done!