I just installed the matte black side vents on my e90 M3. I used a small putty knife, inserted by the tail end by the door, on the top side, in the small slit between the honeycomb and chrome piece. The blade of putty knife slide right in. With some slight downward pressure, the two clips on this end of the chrome piece popped out. You can then use your hands to wiggle out the rest of the clips. I was able to get just the chrome piece out of the car, while leaving the honeycomb in. Just a quick note, once I unclipped the wiring harness for the turn signal lamp, I used a piece of blue painters tape to tape the wire to the car, because it kept wanting to slide back inside.
2011 E92 335is Crimson Red/Black, DCT
2008 C63 AMG
Gone: 2008 E90 M3 Alpine White/Black; 2011 X5 35d Alpine White/Black; 2005 E46 M3 Vert Jet Black/Cinnamon; 2009 Audi A5 Brilliant Black/Black; 2008 E90 335i Alpine White/Terra