This isn't really possible right now. NUKE only responds to GUI events, and doesn't monitor any files or listen on any ports for commands. One thing you might be able to do on Windows is programmatically simulate the dragging and dropping of files onto NUKE's main DAG window through the Win32 API.
It would be nice to have NUKE be able to listen on a port and accept a connection, and accept input from that connection as TCL input, just as if if was from the console. In addition to allowing other programs to send commands to nuke, it would be very cool to be able to remotely "telnet" directly into NUKE, to perform processing or troubleshoot.