Maemo mapper uses gpsd, which has a command interface on port 2947. My own minigpsd emulates it but osso-gpsd in the maemo archives is what is on the tablet, and other variants of gpsd exist.

Basically you need to open a listen port at tcp:2947 (and/or a unix port by the same name that osso-gpsd uses) and emulate the responses after a connection and command. There are several commands and variants to get data and I don't know which ones MaemoMapper uses.