yes. you can definitely do this, actually, i posted a bulletin months and months ago suggesting for people to do this. Just plug your phone in to the aux input via the adapter that comes with the phone and then a 3.5 mm plug and leave it in the center consoule.
except there is one major problem with your idea. the w880 PROBABLY will NOT connect to the e90. I have a SE P990 which is about 6 months old and features bluetooth 2.0 or something, it will not connect to my e90 which only supports 1.0. The w880 is obviously newer, so will have the same version bluetooth as my p990 and doubtfully will connect.
2006 325i Sparkling Graphite Metallic-Black Leatherette
Navigation-Bmw Assist Automatic-Xenons Carbon Fiber Front Lips-Aluminum Pedals Power/heated Front Seats
5% Tint all around 30% On windshield all the way down