OK, I did some testing.
Modified my macro to display the value of Var(2002), the probe trip point, and compare it to the Z axis DRO where the Z axis stops when probing.
When probing at 10ipm, the Z axis DRO reads .0035" lower than the trip point.
So a macro using the GetVar(2002) would set Z zero exactly at the top of your work, a macro using GetOEMDRO(802) would set Z zero .0035" below the surface of the work. (At 10 ipm)
The slower the probe move, the closer the values become.
At 1ipm, the deviation was less than .001".
So I guess that you could get acceptable results by substituting GetOEMDro(802) for GetVar(2002). But be aware that the results you get may not be correct, but they may be close enough.