ow... lol

Well, to be honest (gonna tell u a secret!), with AHK, Keyclone and stuff u can use everything, A-Z, 0-9, numpad, F1-F12 etc etc etc

People are using keys like numpad because for example keys 1-9, with shift and alt and some other keys are basically not enough for 5-boxing (or even less-boxing :P)