3M # 94 tape primer will do the trick. Google search it and then go to the 3M
home page to find a local distributor. Someone on this forum recommended a tape seller on the web but I can't remember their name.
Don't use the spray can version unless you're really good with the masking job.
By the way, the primer goes on the wall paper attached to the wall, not the boarder falling off.
If you can't find the primer, go to an office supply store and get # 924 adhesive transfer tape and put that on the wall. (3M # 924 is also known as #987, or # 465 - same 2 mil adhesive)
Clean the wall paper surface too.
Don aka Mr. Sticky