Look at the code in cyCircled (
http://www.wowace.com/files) for ideas. This mod has several textures for Bartender2 (as well as the Ace2 version of Autobar, Bongos Itemrack, TrinketMenu, XAD) butttons (circled like BT2Circled, Sprocket, Gloss, etc). The mod is still in beta so the code may have some bugs, however it will give you a good idea where to start and may even provide the platform you need.