Ahh, the always popular world of Unix serial programming. While I've not done it on the empeg, (and it might be different since there's otehr stuff happening on the serial port), the following guides I've always found to be useful:

http://www.easysw.com/~mike/serial/serial.html
http://www.stokely.com/unix.serial.port.resources/serial.card.code.html#code.link (toward the bottom)
http://astronomy.swin.edu.au/~pbourke/other/serial/

I'm sure you can find more by searching for ``Unix Serial Programming'' on your favorite search engine.