Connect the programmer using serial port and start a PC terminal program.
Page 20/70 has cable examples.
Xon/Xoff is supported so
Tx - Rx
Rx - Tx
GND-GND
cable can be enough.
Character format 19200,8,N,1 is pretty standard.
Page 36/70 is Remote Control.
If no software is available that is your only way.
Page 38/70 has a send data example.
There, after those few initial characters, you just pick the file with correct format and click send in terminal program.
The programmer then send something back when ready.
Raw binary file format is faster than any text based thing.