Hello Ascension64. Thanks for all your work on this mod!
The mac equivilent is the command-line executable tisunpack, which the WEIDU installer puts in the /bin/ directory (along with the weidu exectuable itself, and sox). They work the same, but you need to call them differently in the .tp2 file.
The most common solution seems to be to use an external .bat file to process tiz files on the Windows side, and a unix shell script on the Mac side. Then within the .tp2 file you reply on the %WEIDU_OS% or %WEIDU_ARCH% variables to determine whether to call the bat file or shell script. It is slightly more work for the mod author, but it works. The G3 forums has a how-to at
http://forums.gibberlings3.net/index.php?showtopic=792 .
With only one file, it might be easier to keep it all in the .tp2 file. The following _should_ work as a replacement for line 565, though I need to test it to see:
ACTION_IF ("%WEIDU_OS%" STRING_COMPARE_CASE ~WIN32~ = 0) THEN BEGIN // if Windows
AT_NOW ~bg1ub/Tutu/TIS/tisunpack.exe -f -s -o override/_AR1010.tis bg1ub/Tutu/TIS/_AR1010.tiz~
END ELSE BEGIN // if Mac
AT_NOW ~tisunpack -f -s -o override/_AR1010.tis bg1ub/Tutu/TIS/_AR1010.tiz~
END
Stay tuned, I'll test this and make sure it works on the Mac end.