There is a way to make it work, even though Jeff's proposal is less of a work-around 😊:
1) Rename your .adp files in question to .ADP ... (I don't believe they are allowed to have an accompanying .tcl file, though. If I'm right, try to move the logic into the .ADP page)
2) Add to the default params for static-pages, "html htm", to look like "html htm adp" (the params are case insensitive).
3) Go to static-pages admin and scan the filesystem for static pages.
4) Restart the server.
5) .ADP pages ought to be commentable at this point.
PS. I've noticed strange behaviour when indexing large amounts of pages (html pages mostly) where the "add comment" link would not show directly. However, waiting till the next day always solved that problem... Perhaps it has something to do with scheduling of the indexing - I don't remember/know exactly.
Disclaimer: I've only tried this on an 4.5 Beta2 install.
