I was going to make this an edit, but there's too much new stuff to say so I'll just make a new post.
-bump-
Well I figured out why the 4th white key does not work in J2K. This is simply because their "left" is actually -x axis when the button on the IIDX controller is refurring to the LEFT button on the D-pad... Sadly, J2K doesn't seem to have THAT set of directional buttons. Only the anolog ones.
Fortunatly, ControleMK does have this. They're called Hat Switches. So just set it to Hat Switch LEFT.... unfortunatly for me... ALL the buttons work perfectly but AS SOON as you enter actual gameplay, nothing works and that PISSES ME OFF TO NO END!!! It even works on the menues and EVERYTHING! But as soon as you start a song in (IIDXsim/DJ MAX/O2Jam/whatever) NO BUTTONS WORK AT ALL and I have no clue why. I have the GameOn converter. That shouldn't be the problem though as everything works fine in J2K... BESIDES THE FACT THAT IT HAS NO BUTTONS FOR D-PAD!!!!
Just thinking about it is making me even more angry. Does anyone have any clue why this is happening? Thanks.
EDIT: I got this thing called Xpadder which seems to work fine... Only one thing... The timing is kind of odd. Is there a way to fix this? LIke in fixing controller properties or something? Thanks. It's like lag or something. Not very big at all, but still, you can kind of fell it when you play.