Alfred, I wanted to help, but when I lifted my grey mat tonight to take a picture, I forgot about all the lead septum I'd laid and really don't want to pull it all up to get to the padding. I can tell from my picture that there is no tab on my car for that hole and it is not broken off. I can't tell you exactly where the dimmer switch wires exit, but I think they travel upward behind the pad. My pad is slightly ripped because I went to the switch to install a relay wire to get the power off of my dash headlight switch and not burn it out. I've attached the high res pic. Now that I look at it, the two green wires travelling up from the switch are mine for the relay, so, I guess I'm not much help here.
Sorry.