I do not think this is possible. I suspect that both the Aux connecter and I Pod connecter use the same plug in on the back of the BMW head unit. So its either one or the other.... If I am wrong please someone correct me!
The DIYer BMW rant:
Cursed plastic impailor waterpumps, plastic bleeder screws, m20 timing belts, anti rattle clips, window regulators, CDV valves, digital odometer displays, evaporative emissions circuit, aux cooling fan, sunroof drains, heator cores, door seals, control modules, M62 cam covers and of course GM autos.... (more to come)