Hi, Jonathan.
The .lit format is exclusive to Windows and Microsoft has not published a version of Microsoft Reader for Mac.
Some Google research appears to indicate that
ConvertLit is the only utility addressing the conversion of .lit to other formats. The tool appears primarily to be aimed at performing the conversion on the Windows platform, using the DOS command line. There appears to be an untested command line version for Mac OS X that was compiled under 10.3.5. The tool itself is designed for command-line use, though the author notes another developer
created a GUI for ConvertLit on Windows.
Note that, depending on where you live, use of ConvertLit may be illegal, especially if the e-books in question are protected with DRM (Digital Rights Management). I've not used ConvertLit, simply found it through researching your question.
Other than the above, I think you're out of luck.
Good luck!
😉 Dr. Smoke
Author:
Troubleshooting Mac® OS X