Mario Beocroft produced a new ST/e IDE interface about five years ago:
http://gem.win.co.nz/mb/atarihw/ide.html
(No, still not on the continent some of us would like him to be on... :)
It worked with HDDriver and also serves as a TOS upgrade. Unfortunately, he's no longer developing and making these things, but perhaps someone could convince him to start again or purchase the rights and materials needed to produce them elsewhere.
There's no explicit mention of CompactFlash since this was well before the digital camera market exploded (1999/2000) but I don't see why you couldn't use an IDE->CF adapter.