I haven't taken off a mirror yet, but I found this view:
http://www.villagetoyotaparts.com/sh...&searchString=
This Toyota dealer doesn't have the best prices, but their parts diagrams are pretty handy (they helped me in replacing the melting liftgate switch).
It looks like there's just the triangular trim piece above the interior door trim panel that's held on with one retainer, and behind that the six nuts and the harness connector. I haven't found an exploded view of the mirror itself.
Have you looked at the bottom of the mirror, to see if there is a screw down there? The part diagram seems to imply that the puddle lamp simply comes out the bottom. The lamp (p/n 81880-AE010) isn't cheap; the Village Toyota price is $39.62, and 1sttoyotaparts.com's price is $35.68.