Legacy keyboards with extra keys and Linux Mint

[SilverNexus]

I am trying to get an old Magitronic FK-5001 (Probably a relabeled Focus FK-5001) keyboard to work right. As I am typing with it now, it does work for most things. Unfortunately, the diagonal arrow keys (which were precisely why I wanted to use this keyboard) that come on the keyboard do not work as I wish for them to. Instead of making a true diagonal, they make a horizontal and a vertical keypress at the same time. In most situations, this would work fine, but it only sometimes recognizes both keypresses and does not perform true diagonals in games like Crossfire (which I wanted to use this keyboard for).
So, I have a few questions, in which any answers would be helpful:

• 1. Does anyone know if the diagonal keys actually make their own keypress? I looked around and found scancodes for most everything but diagonals.
  _ a. I suppose I could disassemble the keyboard, but I'd rather not risk breaking or damaging anything. They sound like they have their own keys, but they may very well be pressing the two adjacent direction keys simeltaneously.
  2. If the diagonals do make their own keypress, is it the keyboeard BIOS or the keyboard driver that would decide to make the diagonal a horizontal and vertical keypress at the same time?
  _ a. I hear there's a way to reprogram the keyboard BIOS, but I'd rather not have to mess with the keyboard on that level.
  3. If it is the keyboard driver interpreting the keypress into two components, is there a driver I could use that would correctly interpret the diagonal keys? (I am using Linux Mint 14.1 with the MATE desktop, if that makes any difference.)
  4. If there is not a driver, is there a way to easily customize the keyboard layout to support true diagonals? (I am using the generic 105-key keyboard layout because I do not have a driver that matches this keyboard.)

If all else fails, I could just switch to a different prrehistoric "clicky" keyboard, but I want to see if I can get this one to work right, just so I have diagonals.

[SilverNexus]

After some more research, I discovered that if I could get XKB to recognize the diagonal arrows as independent keypresses, I just might be able to get this to work.

Anyone know if you can add key functionality (e.g. a command for up and left simeltaneously, rather than two seperate commands) in XKB and not break it?

Since this is getting more version specific than it was before, I will note that I am using Linux Mint 14.1 32-bit with the MATE desktop. (I guess I did mention it before, but I missed it on my preliminary scan, so I'll leave this here for easier reference).