Hi Johnnydog
Sorry I only have ones where the housing is removed. This was on a 1995 Omega, but I cannot see it being any different on the later models.
There are three small flange nuts, inside the car. As looking at the housing behind the glove box, you should be able to see them once the glovebox is removed. I also took the piece of trim out under the glove box, for more access. It fits into some plastic clips fitted to the bulkhead. I didn't have to remove anything else. The nuts are a flange type and a size 10 spanner if I remember correctly, I used a small ring spanner for ease of access. Then a long socket to finish them by hand. One of the bolts that is molded into the housing, was just turning on mine. So once I got the other two nuts undone, I gently prised the housing off the bolt. When refitting, I used some seam sealer around the, foam gasket on the housing and pushed some into, the hole where the bolt that had come out went. The nuts were done up to where they felt tight, then just a little bit more. I didn't overtighten incase the other bolts decided to start turning. Once it was all tightened back up it has not leaked. Hope this helps.
If you use this photo looking in the engine bay side of the scuttle, where the housing has been removed as a reference. You should be able to see roughly where the nuts are inside the car. It wasn't a hard job, just a bit fiddly especially the top one.

The housing off the car, showing the captured bolts. And the hole where the other one, that was turning was meant to be.
