You mean change the color of the halo rings? Like from the Yellow (4500k) to white (6000K) or White/Blue (8000K)?
White blue, I dont know, but there is a company that sells a kit to change the OEM ones to 6000K white ones. I ordered a set for my E60 545i. Awaiting delivery. With the new BMW's (E90, E60, etc) any that come with halo's preinstalled just need to have a bulb changed out to change the color.