I do this quite often for channel letters, etc. Run duct tape (cheap is OK) around the perimeter of the pattern plus a few spots in the center. Go up in the bucket truck or lift and use a staple gun (3/4" long staples are better than the 1/2" ones) to apply the pattern to the wall. Put the staples into the taped sections of the pattern. Doing this will make pulling down the pattern and staples easier. Also, use SS staples because you can miss one or two. The std ones will rust in short order staining the wall. If the pattern is made with really thick
paper you can even skip the duct tape.
Or use the extra wide Gorilla tape. Its about $15 a roll but worth the money. It sticks in all but the coldest weather. Just a couple weeks ago I did a 3' x 30' pattern (and that's not really that large) on eifs with this method. I know guys who have done patterns up to 100 feet long with tape. Bring a rubber mallet (or an extra roll of duct tape) and tap the tape to get a better hold to the wall.
Some guys like to start in the center of the pattern and work out from there. I prefer to start at one end and keep going. Whatever works for you is best.
I would go with the other methods (gluing to a stiff background and screwing to the wall) only if you must work in the rain or very high winds. However if it's that wet/windy I'm probably rescheduling the job.