How to Change What a Keyboard Key Returns
 

I have a standard PC keyboard, with the usual number pad on the right hand side. This number pad has /, *, -, + and ENTER keys along the outside of the actual number keys, just like all other PC keyboards. On Mandrake 10.1 CE, each of these keys, when pressed, generates a long sequence of about 5 key codes, start with ESC. Under SuSE and Yoper, the same keys, when pressed, each generate a single key code like 0x150 or some such.

Can anyone tell me how to modify what is returned by each of these keys? The extended ESC sequences are messing up a favorite editor of mine that uses these keys. I am assuming that there is some form of xmodmap command that I could use? Any and all help much appreciated!