Ok, I finally solved auto-closing sunroof. My 26€ keyless entry module works great!
I soldered a wire on the "locking" relay located in the keyless entry module, at the coil pin, so I got an "aux output": +12V for 2 seconds when I lock the car.
But 2 seconds are too short for the sunroof closing, so I installed a timed relay that powers up for 8 seconds. Then I found that this timed relay only has 1 contact. The sunroof needs +12V on 2 contacts to close.
I had to add a last standard-type 12V relay for closing 2 contacts (close and power to sunroof motor).
Now, when I close the car, the keyless module powers the timed relay, and this powers the last relay that gives +12V to the sunroof motor. It's great!
I wanted to avoid direct connection to the sunroof motor connector, I should have grounded a wire on the Convenience Control Module, to emulate key in the hold-close position to close the sunroof. But I didn't find the correct one.
Nevermind!
Here is the schematics.

Attached Thumbnails