I posted awhile back about Atmosphere and Trilogy not being ported to Mac Intel, and in Eric's reply he mentioned a workaround would be posted.
It was, I've implemented, and it works great. This is how mine is set-up:
Plogue Bidule (Rosetta) on Mac Pro, hosting Trilogy and Atmosphere.
ADAT lightpipe out and back into my interface and into Logic.
Midi from Logic to Bidule using the Bidule internal MIDI ports (instead of IAC, though presumeably that would work also).
CPU usage more than acceptable, and it's been solid (a few hours use).