you do have to take off the valve cover. I don't quite understand how it is stuck on. the studs are screwed into the head and then these little 10 mm nuts on top of these dinky little plastic washers hold the valve cover on. Is it possible that the the seal is just stuck and holding the cover on? if so yeah just get a big screw driver or something and start in a corner and pry it off.
Seems to me if you snaped some of the bolts off it would still come off. Even if those nuts are badly rounded a good pair of vise grips and some PB blaster should get them off no problem. Im not positive but i think the holes in the valve cover are bigger than the nuts, so if you got a benzomatic torch or something you could burn the washers out and then the cover would come right off. That is if you really don't care what happens to the cover.