Can I dripfeed to my CNC with DNC Software?

Yes, DNC Software will allow you to dripfeed large part programs that exceed the memory of the control line by line.  This is like streaming the code to the machine.  The software can be configured to support XON/XOFF (software handshake) and RTS/CTS (hardware handshake) protocols.  Depending on the controller, you may have to use XMODEM or other machine-specific control protocols to allow dripfeeding.