Well, if you have a Release 7 or 8, there is the serial Administration port. If you can get the serial to ethernet adapters to talk to each other over the wan, I don't see why not. As long as you're attached to Com 1 or 2 on the admin PC, you would be fine.
Alternatively, how about a PC on site, with a serial port attached to the Admin port, the programming gui loaded on it, and LogMeIn so you can access it from anywhere.