If the hairspray can's nozzle has the little hole to fit a WD40-type extension tube it's a snap. If not, spray some on a long thin blade screwdriver and work it around. May have to do it a few times, but I've always had good luck with that. The upside of using this is that when fitting the new grips, just give a small shot to the inside, work it around the length of the grip, then quickly pop it on the bar. As you mentioned, it'll lock the new ones on good. If WD is used, you have to really get it all off the bar or the things won't stick well.