Painting over wallpaper
I am going to do some painting in which one room has wallpaper. The owner does NOT want the wallpaper removed, she wants it painted. Apparently there was a wallpaper removal project in another area of the house. It seems the paper was not installed correctly, maybe over bare sheetrock. Anyway, it came off in postage stamp sized pieces and left the walls a mess. She does not want to go through this again. I have only done one other paint-over-paper job, and that was in really good shape and went well.
The wallpaper is in good shape, appears to be well adhered, without any peeling. EXCEPT. The room is three sided, with a large open entry on the fourth side. So, where the room wall meets the hallway wall at an outside corner, the wallpaper just stops. At this corner, the paper is a little worn, and maybe 1/4" or so has pulled up. I will need to stick it back down before I paint. My question is, what is the best method to re-adhere this area, of perhaps a few feet of height by 1/4" wide?
I am planning on two coats of primer and two coats of paint. Please advise any other steps I need to take to make this a success. Thanks!