The problem with that is that this folder has 110mm spacing (or so I assume, he used a BMX wheel), and most track hubs are 120mm. Plus, take into account the ridiculously short stays, and bending the frame that much becomes a real hassle.

So, the only REAL way to get a safe fixed hub on that bike is to find a 110mm keirin rear hub ($$$$$) or convert a 120mm hub by removing spacers (Suzue's and DA's, usually). Either way, a boatload of cash for one lousy tiny wheel.

Or, you could just keep using your suicide wheel with a brake. I did it all summer with a rotafixed blue loctite wheel. Not much skipping or skidding, but it held anyways.