This subject comes up quite often, especially since Pigtail began offering steel bushings. I hear people talking about prying bushings out, the thought of which makes me cringe, so I thought I'd share my method of pulling bushings. If anybody's got other suggestions, feel free to chime in.
Like many things, it's relatively simple providing you don't screw it up by doing the wrong thing. Whatever you do, don't pry. Even with padding between the prybar and the guitar, you may dent the wood or distort the holes by pulling the bushing out at an angle. You want to lift the bushing straight up, just as it went in.
First of all, the lacquer finish will be covering the top of the bushing. You need to use an X-acto knife to carefully score the lacquer around the edge of the bushing so that you don't lift a big chip of the finish from the surrounding area.
Here are the tools I use, which is just some crap I found in my junk drawer. The yellow part is a rubber garden hose washer which contacts the top of the guitar and protects it. The chome nut is part of a plumbing coupling. You could also use a stack of large diameter washers. Just make sure the hole is big enough to allow the bushing to pass through them. Next is a smaller washer that seats underneath the stud. Once you have these parts stacked up, you simple thread the stud into the bushing and tighten the stud. The screw threads have a good mechanical advantage, so the bushing pulls out relatively easy.
Make sure that you use a large screw driver to prevent scarring the slot in the stud. Wrapping paper or masking tape on the blade helps. It's also a good idea to cut a hole in a piece of cardboard and tape it to the top of the guitar to protect it in case you drop a screwdrive or washer while you're working.