Do you have a plastic valve cover or aluminum? I wouldn't be hitting it with a ball peen hammer at all. If it is warped, I'd get another.
Never use a wire brush on the top of the cylinder head unless you are prepared to dig all the steel or brass strands out of your cylinder head from the wire brush. Put an old towel, one that your wife doesn't need in the house, and lay it on top of the cylinder head, only exposing the gasket surface you will be working on. Use a straight edge razor/scraper and gently peel any old gasket material off. You want to be gentle and take your time. If you scratch the surface, it is OK. Just don't really mess it up, by gouging it severely.
Clean the valve cover with cleaner and a flat-head screwdriver. Use a cleaning solution to get it really clean. Now use an old racer's tip: Use RTV silicon on the valve cover only and put the gasket onto the valve cover. It should be the last time you ever have to replace that valve cover gasket again, until you are ready to rebuild. And then, the gasket will come up easy without any mess left on the cylinder head.
Last thing... do you own a jeep manual? If not, go buy one. Chilton makes a decent one. It is not the factory OEM manual, but it is better than nothing.