Bioforge uses the Ctrl and Alt keys with the numpad for hand and feet combat so using modifiers is going to result in some serious finger contortion!
On all the keypad-based systems I've mapped this way, most just use keypad input for menu options such as player and difficulty selection, which can be casually selected. However, I can definitely see why mapping a game like 'Bioforge' this way wouldn't be any fun. Intellivision games often make the keypad an integral part of the core control scheme as well and I sometimes find myself doing mental and finger gymnastics in order to simply move a character from left to right. I end up having to tailor map a custom control scheme if I want to play the game any further.
Anyway, I'm glad you found an option that works for you. It does seem to be the best solution.