I don't have a keypad, but I do have a Gamepad. I usualy use it to TS caps.
Anyway, since Freelancer itself does not allow usage of anything other than keyboard/mouse, I'm using a program- Pinnacle Game Profiler. It allows to use any gamepad with any game, by mapping the gamepad's keys as the ingame keys.
Pinnacle may not work with your keypad, but you can look for other similar programs.
Also, Pinnacle is not free. I use a cracked version. If you wanna use a cracked version too, look me up on skype.