Throw out the manufacturer-provided software. If you have installed it, uninstall it. If you have not installed it, excellent. You have spared yourself a close encounter with hideous user interaction design.

If you have SteerMouse installed, remove it because it'll conflict with USBOverdrive. SteerMouse is great for regular mice, though, so do not consider this a slam on this excellent software.

Install USBOverdrive. Pay for a license. The author deserves it.

Visit the USBOverdrive system preferences. Do "New Duplicate Settings" in USBOverdrive's main menu popup. Choose the MMO7 as the device you want to configure. If it doesn't appear in the list of devices, you need to uninstall whatever USB device wrangling software you still have installed.

Methodically press every one of the MMO7's buttons. Assign it an action or a keystroke.

Repeat 5 until you have all zillion buttons programmed.

You lose the ability to make macros with this approach, so if you need macros you might have to figure out how to make the Saitek/Cyborg/Madcatz/whoever the hell they are software work, which I was unable to do.

I still haven't figured out how to prevent the "ActionLock" buttons from screwing up left-clicking. They're probably handled directly in the mouse hardware, which is sad because those buttons are in prime real estate right under your clicking fingers.