Xbox 360 controller - Z trigger problem

As many people have noted before; the left and right trigger buttons are bound together as the z-axis, and there is effectively no way to read them as separate buttons. Our temporary solution has us treating z=1 and z=0 as separate events, and linking them both to two functions that the player is unlikely to use at the same time.

Supposedly, the 360 controller works with marble blast ultra (with both triggers working?), and it is known that certain modifications have to be made to the input code to get it to work. We, for example, have mapped all of the SI_POV inputs to a single variable, which reports each of the 9 possible POV states.

As has been suggested, I've been trying to "intercept" input data from the controller. However, it seems as though once the data gets to DInputDevice::buildEvent, the triggers have already been routed to the z-axis. The problem begins right at the beginning: the controller is seen as having 5 axises, when it in fact has 6.

Is there a lower level where we can read the input data directly? Is there any use trying at all, as long as the windows drivers only see the 5 axises? I suspect that anything and everything input-wise comes through DInputDevice::processAsync, but I'm afraid of what would happen if I tried to manually read the eventBuffer.

(Then again, any data that came through processAsync that was not recognized would cause a fatal assert in findObjInstance...)