Perry, file a flat head screwdriver sharp on one side only, then drive it between the front seal plate and the seal in a couple of places. You should be able to pry it out now. The rear one needs a small seal puller and requires for you to pry it out, don't be gentle, you are not going to reuse it.
Harbor Freight and a couple of places sale these in about 4 sizes in a pack. They work for several things so invest in a set.
Wayne
Perry, as a side note, have you ever checked the rear spot welds on your Z3, in the trunk toward the front of the car. Check it out on the net, it was a bit issue as they hold the whole rear end in place. Wayne