All I can suggest is that you read the instructions on the wallpaper packet you get. That should tell you the type of 'surface' you can put your wallpaper on. The glue, for example, may not bond well w/a non-pourous surface. Then again, it might. If you have to, ctc the mfgr. of the wallpaper for advice. Be SURE to get a name so that if it doesn't work, you know who you talked to. (Write it on the roll, or something.)
I would like to tell you to be careful where you install your wallpaper. The vinyl may shrink if it gets too near to heat (over time.) And, the glue may get soften up too (over time) where you'll experience 'sagging'. The vinyl wallpaper has these tiny crevices too that prevent a good cleaning should stuff like pasta gravey get splashed on it, and the like. Yes, it can stain. Sorry to say all this but you might want to reconsider tiling. Personally, I think it is the best thing for a kitchen backsplash. Sure, you can't 'change' it like wallpaper but it's much more durable and easier to clean. (You didn't ask but) Have you considered 'mixing in' some designer tiles on the backsplash along w/the tiles you picked out? In our kitchen, my wife bought these 'granite-type' white tiles, and she intermixed just a few tiles that had Spice Plant Mosaics on them. It kinda gave some character to what would have been a 'bland' (all plain white) backsplash.
Those are my thoughts. It is your kitchen. My best to ya and hope this helps.
Jay J -Moderator
PS: There are plenty of Kitchen & Bath magazines at the Newstands. Maybe you'll get some thoughts on both wallpaper and tile ideas ...