Compressed air is great for removing golf grips too! Just wrap a thick magazine around the grip, inject the air and off it comes....you can also save motorcycle grips this way...the mag keeps the grip from over-expanding.Compressed air is your friend. just peal up the inside corner of the old grip and blast the air in there while pulling / twisting off. To install, the same in reverse.
If a compressor is not avialable you could just cut off the old Being carefull on the throttle side of the throttle mechinism. Then using lightly soaped water slide the new grips on. If using this meathod don't ride for at least 24 hours since they need to completly dry out first.
+1 on that... just don't go cheap-o on the hairspray-get a high propellant can. I went cheap and the stuff never dried up. My grip was slipping all over. I had to remove them and underneath I found grimy black liquid that the stuff turned into.+1 on the hairspray. Been doing that way for 20+ years. Never had a grip come off inadvertently either. I'd have made a squishy if I had one come off in a wheelie! :O