The WTK from sun supports MIDP2...
http://java.sun.com/products/j2mewtoolkit/ I believe you could change the skin of the emulator by modifying the image it looks for in the devices directory. All the different emulators are in a directory named devices under the WTK root directory. I don't have it installed right now or I'd check, but there should be a set of png or bmp files there, which you can edit to be all black (or whatever).