Go to Sears and get an Impact Driver. Don't use the cheapo crap from Harbor Fright for work like this. If you have buggered up the screw heads, then about all you can do is drill the screw out. Go careful, starting small and working your way up in drill bit size.
I've removed several bar ends with the heat gun, never had a problem. There is an unnecessary amount of red loctite on these screws, not sure why they use so much.

scootertrog

 

to pull mine i just used screw bit that fit inside a socket, then put the ratchet on there and off they came...