Run make compile to generate the binary transport.
./transport $FILE | sox will cause it to be emitted as sound.
If you plug your audio jack into an Apple IIe, this will have the effect of transmitting the data to it. Make sure you're in the right mode to hear it!
This is a direct port of code from ADTPro, which has the GPL license. So, even though we (@mtornwall) and I hate it, we begrudgingly release this as such.