This is too late now, but a trick I use when I run in to a bolt that is really hard to loosen (and before I strip the bolt or nut), is to give it a sharp rap or two with a ball peen hammer axially - not side to side. This will often break the bolt loose and allow you to remove it with your wrench normally. Of course you must use caution and common sense as to how hard you hit the bolt and how you strike it...making sure you don't damage the bolt head, the material it's bolted into (soft aluminum?) and surrounding objects.
As far as extracting a stripped bolt, I find that ez-outs are very difficult to make work. Make sure you don't end up with a broken case-hardened ez-out stuck into the top of your stripped bolt.
The method that Jeff mentioned is the one I've had the most luck with. Sometimes, if you have enough access, a hacksaw can be used to cut a slot into the top of the bolt head.
Of course if none of these methods work, you probably will have to drill out the bolt completely....a difficult task at best (and really a pain if you have broken off an ez-out in the bolt). You have to use a pilot hole first *exactly* in the center of the bolt and then use a big enough bit to get most of the bolt, but not the stuff it's bolted into. If you damage the head threads, you may want to get a machine shop to intall an insert (HeliCoil).