What kind of UART is in the empeg?

Strictly speaking, I can live without RTS/CTS but this is only because I'm running PPP and it is easily restarted. It appears that when an overrun occurs my serial device (a CDPD modem) tends to hang and then reset. The delay while it resets and PPP restarts is on the order of 10-15 seconds, but with large file transfers this tends to happen rather often, dramatically diminishing my overall throughput.

I'd like to see RTS/CTS enabled, and I'm sorry to learn the harness lead doesn't have these lines connected. Is it feasible to modify the harness to connect them?