I just went through the same ordeal this past weekend.... I have a console and loaded PEB, but with no modern hardware like HDX boards, or floppy emulators. I have a Terminal Emulator II cartridge and tried to transfer between the TI and various TI emulators on my PC, but didn't have much luck for whatever reason. I ended up typing in a crude assembly program that was listed in the October 1989 Micropendium magazine. It uses Xmodem and can talk to Hyperterminal,etc on a modern computer. I compiled it and was able to transfer MagicFM using this terminal emulator on the TI and Qmodem Pro on a PC. As long as you have an E/A cartridge, RS232 card, and some kind of term program on your Mac that supports Xmodem, you should be able to transfer files and open up more possibilities.
Quick and Dirty RS232.txt