This will be really hard, but find the Logitech MX 1000. This mouse is no longer sold (no idea why) ... but it is the movement answer to your issue. It has 3 thumb buttons (I use the front for AutoRun, middle for PTT, and the back for back up) I set the side-scroll to be 'q' and 'e' for strafe and then I steer with mouse look. Works great for me . I am currently trying out the "MX Revolution" - but it actually has fewer buttons. In fact, I would love to know if anyone has found a mouse with as many buttons as the MX 1000.