Does anyone knwo if it possible to do the PDC sensors from the outside??

When I bought my X5 the rear center two were missing. Kind of pissed me off when I found out these lil suckers cost $100 each from the dealer!! Well low and behold when doing some cleaning of the X5 I found "something" in the glove compartment. Hummm... yup, turned out to be one of the PDC sensors!! Cool, now only one to buy!!

Today while I was doing the rear wiper mod I decided to mount my sensor that I bought the mounts for. While I was doing that I tried to find the wires for the other sensor.... and...... the other sensor is hanging there on the inside of the bumper!!! Score!!!

Now I just have to mount them.

If anyone knows if you can mount them from the outside, great. If not I will tkae El Jeffe's advice and the bumper cover comes off tomorrow!!!