They are sticky as far as I know but you use soapy water to apply them, sorry but I can't get my head around that but it's genuine info. The soapy water allows you to slide them and avoids them accidentally sticking where you don't want them.
I've seen this done ... should be interesting 
I used to go out with the reps of a company for which I worked. One of the tasks was restickering retail windows with company advertising banners etc. They all used this method as you'd just never get the huge stickers on without it.
Just light spray onto surface with soap solution, move sticker around until positioned, then lightly with a squeegee push the liquid out from centre to edge to get perfect position and none of the dreaded bubbles
