I just did mine, following the e90 post DIY. Just be extra careful when you bend back the front bumper to get to the lower tabs. It kept feeling to me like it was going to tear or crack, but thankfully never did. I popped the top tabs out with a small screwdriver easily; thought they do have a tendency to pop back in place if you're not holding the grill taut from the front side. The 2 side tabs were the hardest to get loose. Once those are all loose, you have to reach down to the lower tabs by getting your arm/hands down inside/behind the bumper and push the 2 bottom tabs in with your fingers. It's tight, but it can be done. It's not nearly as tight as trying to change out the H8s for the angel eyes.
One thing to watch for when putting the hex screws back in, the bumper can slide forward/back to adjust the seam with the headlight assembly. Make sure it's flush, otherwise it'll look gappy. I didn't realize that until I had put it all back together, and thought I had jacked up the bumber by pulling on it, before I realized I could just adjust the spacing.
P.S. - Matte Black grills look so aggressive and sleek on a JzB. Love em!