Cut them out. For an aged look, dip the paper in a cold tea or coffee bath. Or color with watercolors, ink or pencils. To create a design, temporarily tape your cutouts to the walls. When you're satisfied, glue.
Wheat paste is the glue of choice, but it's strong.
Once the paper is attached, you'll need wallpaper solvent to take it down. Finish the walls with glaze or lacquer. All rights reserved. Any copying, redistribution, or retransmission of any of the contents of this service without the express written consent of Philadelphia Newspapers Inc. is expressly prohibited.