A friend of mine laced a 32h rim to a 32h road hub, keeping the drive side laced 3-cross and lacing the nondriveside half-spoked radial. The effect was similar to a G3 lacing. This was for a road wheel.

But yes, trying to calculate the spoke lengths for a rim with nonstandard drilling sounds like a pain in the ass, or reliance on a very patient geometer. More difficult, I imagine, than with a rim where the spoke holes are evenly distributed.

As other people have stated, the Campagnolo G3 lacing is designed to deal with the different tensions that the drive side and the nondriveside of a road wheel encounter. Putting driveside forces on the nondriveside of G3/triplet lacing (as you would presumably do at some point with a "flip flop" hub laced thusly) would be... not ideal, and potentially bad.