just what hacked said
get a good air hammer and they just buzz right out in about 10 seconds
when i did my kit i didn't have access to an air hammer and man did it blow, i used a hammer and it took forever. Now when i install kits at the shop its just buzzz and its out its awesome.
But if no air hammer, you gotta get something so you can either pount on the metal lip on the outside or the metal sleeve on the inside, hitting the bushing won't get you really anywhere.
Matt