Use wallpaper glue (comes in 1 gallon containers... roll it on with a small fuzzy roller), you might find it to your benefit to seal the maps with a latex based clear varnish (like Minwax Polycrylic or similar... just roll it on with a foam roller in satin, semi-gloss or gloss). You need to be able to wipe it clean. Make sure the stuff is completely dry (allow a few days) before you seal it.
Using wallpaper paste means you can strip it off if you decide you are tired of it or it gets too damaged. Use a latex primer under the wall covering first. Mine is still well stuck.