if you have wavelan, i assume you can get telnetd, and at that point it's a trivial matter to capture data by telnetting in and reading the serial port.

I posted a gpsd binary a while back. Install them, but do not hijack exec them.

telnet in. run gpsd -p /dev/ttyS1

at that point you should be able to telnet to port 2947 on the empeg.
type "R" at it and it will start streaming NMEA sentences at you. Capture them.