Spectrasonics has developed an support solution that allows Atmosphere and Trilogy users to use their original instruments on Intel Mac computers. The free Public Beta version is now available for download in the Support Knowledge Base.

http://support.spectrasonics.net/viewforum.php?f=15

This “wrapper” solution allows the existing Atmosphere and Trilogy virtual instruments to be used on an Intel-Mac computer. It has been tested with a variety of hosts, computers, versions of OSX, buffer settings, etc. Included in the download are performance charts for each of the major hosts and guidelines for users to get the most out of their specific computer setup.

This solution is designed to be nearly identical to the native plug-in experience - with the MIDI and Audio routing working automatically and plug-in settings saved and recalled with the song.
More info:
http://www.spectrasonics.net/news/