How should I go about covering an entire room in black material?
4 feet wide and 200 feet long roll of black paper for less than $25: http://www.amazon.com/Spectra-ArtKraft-Duo-Finish-PAC67304-Pacon/dp/B00006IE1U

I would use painter's masking tape (the kind that peels back off without peeling the paint off the walls and does not leave a sticky residue) and make little rolled tubes of the tape to stick the paper to walls and ceiling, so the tape does not show.