It CAN be done with Hyperterminal, but it ain't pretty.
1. Create a New Connection... call it Kia or Fanuc or Betty.
2. Connect using: COM1, COM2, etc.
3. Set Bits per second, Data bits, Parity, Stop bits, to match your CNC comm parameters. Set Flow control to Xon/Xoff.
To receive from the CNC, you'll have to use Transfer - Captuer Text... then give it a path and filename, and click Start. Go to the CNC and punch the program.
To send to the CNC, get the control ready (READ), then at the PC, use Transfer - Send Text File... navigate to the file you want to send and click Open.