I actually got it to work on my MacBook using Wine (http://www.winehq.org/). It seems to be working fine, although I just tested writing a few notes and exporting it to an NSF file. However, there is quite a bit of lag when playing the song in FT, which is very annoying, but the exported NSFs are of course perfect, so it's not that big of a problem.
jsr, maybe you could look into the lag issue with Wine? That seems to be much less work than, say, porting it from the ground up. Many Windows programs these days are ported to Mac/Linux using Wine (Spotify comes to mind, a music player).
As far as I know, Macs have a program called Boot Camp which let's them use ANY OS they want. If you have a copy of Windows (preferably XP), you can run that on Boot Camp for Mac and there you have it! I have a Mac but it's a G3 tower with OS 9 and I have two old desktops with OS 8.5 but I have a Windows XP machine.
Boot Camp, Parallels, Darwine, WINE Box... There are many ways of running Windows programs on a Mac, thus making the idea of porting the program to a different OS very unnecessary.
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Technology: the one thing that's hated & cursed at by all engineers, technologists, scientists & technicians!
WINEBottler says Intel only right on the web page. Darwine does not run Windows applications (.exe) (it states you cannot run Windows applications using this release on PowerPC hardware)...
If this application ran on DOS, I could actually use DOSBox and run this!