Isso parece um trabalho para AutoHotkey ! Em vez de reinventar a roda eu mesmo, o usuário gwarble nos Fóruns do AutoHotkey já criou um aplicativo que faz exatamente o que você quer:
EitherMouse
- Multiple mice, individual settings...
- New features means EitherMouse isn't just for lefties anymore!
- Leave 2 mice on a pc and automatically swap buttons on the secondary mouse
- This allows a user to leave a left-handed and a right-handed mouse always connected and ready to use, or...
- Useful for a multiple user or public workstation with both left and right handed users. the active mouse is detected and buttons are assigned accordingly and immediately
- Individual settings for multiple mice besides swapping buttons, like cursor, speed, etc
- New experimental MultiCursor mode keeps each mouse's location seperate!
- Easily swap mouse buttons from system tray if only one mouse is desired
- tray icon points to active mouse