Setting Up Crossfaders Between Decks A & C

Can anybody help me with my TSI?

I am simply trying to set it up such that I use "three cross-faders"

This is accomplished as the normal cross fader is between "A&C" and "B&D"

Then the two secondary cross faders (believe where the volume fader for each deck normally is):
Left: Between A and C
Right: Between B and D

How can I accomplish this? Anytime I try and use the "Assign X-Fader Left/Right" the command works fine except when the cross fader is all the way to the left, and likewise when the volume fader = 0. When this happens it just resets to the normal x-fade between "A&C" and "B&D"

I hope this explanation wasn't too confusing