Do you want it to be easy?
Do you want it to be fast?
Do you want it to cost almost nothing?
Do you also want it to be not too too tacky?
I did mine on top of some burlap that I already had up and I hot glued it to the wall through the holes in the burlap. That's just because my painted panelling walls are eventually going to be coming down so I just go after them with the glue gun and reckless abandon all the time.
I've said it before and I'll say it again: You can attach fabric (or ribbon) to your walls using just spray starch and your iron. Really! Try it! And it peels right off!
I picked up a roll of this wide plaid ribbon on clearance for about $2 and cut a few pieces in gradually increasing lengths. I put them out on the floor and stopped when it looked like a Christmas tree.
Stick it on the wall and call your large-scale Christmas cheer done!