Hi Phil,

Dunno much about what's available for astronomy software on the Mac. But
you might give a try to Wine:

http://www.winehq.org

This is the solution I (and many others) use for running Guide on Linux.
Wine has also been used for running Guide on OS/X, though not as much.

There's a bit of discussion of how to get Wine to run on OS/X here:

http://wiki.winehq.org/FAQ#head-5bba8bcc401e4ee1d3b733501f98768a47e661e6

Apparently, it's not as simple as it is in Linux, but it doesn't
look too hard. Getting Guide to run once Wine is installed is, fortunately,
quite straightforward. This isn't true for all Windows software, but I've
put some effort into ensuring that Guide and Wine work well together.

-- Bill