Xbox Controller Hack Question

[theCoder]

I'm finishing up an Xbox based driving cab, and want to put a single button on the dashboard to perform an IGR.  Has anyone pulled this off?  Basically wiring the start, back, left trigger and right triggers into a single switch.  I've hacked three controllers so far, all with different results.  The closest I came was...

On the start and back buttons, I found the signal side of the contacts and soldered a diode to each.  Then connected the ends together, then through a switch to ground.  With a controller plugged into port 1, and my hacked controller in port 2, it would reset if I pressed the button, while holding the left & right triggers.  Cool, got it for the buttons, now for the triggers.  I found the ground line of the pots, and put them in series with same switch (with a diode pointed towards the ground side on each).  This works on most games, but I get weird results on some.  It is as though one or more switches are engaged, but I think the diodes should be stopping that? 

I've also tried wiring all four leads to ground, then switching the Controller Data+ line.  This didn't work either.

Any help would be appreciated.