I do not recall any way to upload from a cassette tape, unless you got your hands on a computer that can load from cassette, then download to rs232.
If EIA option was purchased with this lathe and never installed Mazak may be able to help.
Mazatrol is extremely capable on a lathe; you may be better off getting a couple of hours of instruction on mazatrol. That would be sufficient to get a machinist started.