I don't have much experience using one, i've searched google for mouse emulator and tried the first i found.
It allows you to control all of the the mouse functions (of a "normal" mouse) with the numeric keypad. And it works together with the mouse.
This one is limited to the extent that you can't change the keys used. But i think that if you search further you might find one much more customizable.
I've downloaded and tested the program and imho it seems safe but i don't guarantee anything.
Sorry for my impetuous response but i have just noticed that in the readme says it doesn't work with direct input.
I'll be looking around to see if i can point you in the right direction.