Dan, you might also want to check out the write up in Greater Magic.
Hopefully, with all these sources, you will find an author who has actually tried to fool an audience with this. It's a dificult thing in many ways, in practice. Remember that sheets stand up by themselves only in illustrations, and if you're planning on doing this with just a plain sheet, at one moment the angles will probably stink.
Good Luck, it can be done, but you've got to be willing to rehearse.