If you just peek over the top of the passenger's side kick panel you will see a 12mm bolt and a 12mm nut/stud, which are to hold the ECU upside down in that location. You need to remove that plastic pan under the glove box, if your car still has it.
This is a not-so-helpful picture from the manual:
Quoting brunoboy:
anyone with pics? Mine has been hanging ever since I bought my car...............