Term X I was gonna look into installing the kahtec lane changer mod.
http://www.bimmerboard.com/forums/posts/820085

seems like it is doable... the OP in the referenced thread did not get the indicator in the cluster to blink, as that indicator blinks via i-Bus command:

Turn signal indicator lamps: The turn signal indicator lamps are switched by a corresponding K-bus telegram from the light check module (LCM) to the instrument cluster.

but otherwise it should work

Term. X that fact that the signal light would not blink may drive me nuts but now you got me wondering if I should put a diode in before back to the lkm. Hmmmmm.