Patrycjusz Łogiewa has taken all the GPL TASM sources from the Maxflash kit and after a lot of hard work has ported them to assemble with the free open source xa65 cross assembler.
With xa65 as the assembler and the new files you should be able to run the maxflash cart maker kit on pretty much any modern computing platform.
You can get the xa65 assembler at:
http://www.floodgap.com/retrotech/xa/
The xa65 version of the maxflash kit sources is attached to this message. I have not yet tested them myself but if any of you are running linux give them a try.
Steve