It's a UART hooked up to a TTL<->RS232 converter.
You'd need something to control the UART however which is where the PIC chip would come in.

It shouldn't be too hard as most of the work in decoding the serial data is done by the UART. You'd just need to grab the data out of the UART FIFO and pump it back out to the empeg.

I don't have the time to do it myself but if anybody else wants to have a go, I'll be more than willing to give a hand.

- Trevor