I agree, just fall and get it over with already! It truly is worse on the ego than it is on the body.

But to get your butt off the seat and get a feel for it, have you thought about going to the park or an empty lot with your regular shoes (or one regular shoe and one cycling shoe) on to just play around and see if getting that butt out of the seat is easier? That way, you take clipping in/out out of the equation and maybe your worry off falling will lessen also since you wouldn't be completely attached to your bike.

I say, just make yourself do it once, and if you fall, the worst is over and you'll be able to tackle each attempt easier after that.