Okay... I'm stumped.

My plate is rattling pretty bad, and the Lancer is the first car I've had that hasn't had four standard holes for mounting the rear license plate.

One of the clip-on screw hole adapters is stripped, so at minimum, I'm going to need to replace that. I've been to two different parts stores, and neither of them had any idea what I was talking about. I even took one guy outside to show him, and he said he had never seen something like that before.

I'd rather not drive an hour or more to the dealer for what's probably a 99-cent part. Has anyone seen these in stores?

Also, the plate I transferred is bent pretty bad (not sure how that happened), and I'd really like to hold it down with all four screws. Is there anything I should look out for before I start drilling?

It probably goes without saying, I really don't want to go drilling in to my new car. At least... not yet. ;)

Mine fell of like the first week I had it. I went back to the dealer and they had no idea what it was either. I ended up using a nut and bolt. It was hard to get on though b/c you can't really get back there to tighten the bolt.
The DMV will only replace plates that are unreadable, so I think its time you got out a hammer!

Well...my plate is still bent, but for anyone who might have a similar problem in the future, I found replacement parts for the license plate mounts.

Napa sells a fastener kit (Auto Fastener Group #4071R). The only downside is that you go from a metric M6 bolt to a US 1/4" bolt, which is really only a downside if you're really intent on having everything 100% metric.