Just found this one, very helpful:
"Mouse Emulator" This program is freeware. If you really like this
program, and want to make a donation, please go to the website for
more information. Thank you.
The program runs under windows NT/9x and above.
The program recognizes the following keys: (NumLock must be ON!)
Keypad 1 - Left mouse button
Keypad 2 - Right mouse button
Keypad 3 - Middle mouse button
Keypad 4, 5, 6, 8 - Moves the mouse left, down, right or up respectively.
Keypad 7 - Mousewheel up (Scroll)
Keypad 9 - Mousewheel down (Scroll)
Keypad / - Toggle Left mouse button (Useful for RSI users)
Keypad * - Toggle Right mouse button (Useful for RSI users)
Keypad - - Toggle Middle mouse button (Useful for RSI users)
Ctrl + Keypad 0 - Enable/Disable Mouse emulator
You can exit Mouse Emulator by right clicking on the mouse icon in the
Adjusting the mouse speed: Double click on one of the .reg files and
restart the program to change the mouse speed. For instance
double-click on SlowMouseSpeed.reg and restart the program if you
think the mouse speed of mouse emulator is too high.
For advanced users: If you want to adjust the mouse speed, you can use
regedit to change the registry values.
Known Problems: Mouse Emulator does not work with MS-Dos prompts (9x)
Mouse Emulator does not work with DirectX Mouse Input (DirectInput)