To switch gear faster than doing it with key presses you would need a macro program, either have it use f1-f5/1-5 with the press of one designated key with like a milliseconds pause inbetween each click. or if the gears are on a tab that isn't the first bar have it point your mouse to each window and using the same method as above. Don't know if it would be against the rules though, also I don't think it's necessary.
http://epicpw.com/guides/macros/
Once you create the macro, you can drag the icon to your skill bar.
The macro in the guide is for auto-attacking with demon spark.
You can just drag over any skill that you like to put in your macro.
You can't macro gear switches with that method, which is what OP is asking