Open up your Sierra Wireless 881U USB modem and you will find a Sierra Wireless MC8781 Mini PCI Express modem card which have builtin GPS. You just need to install it in your Mini 9 and update it with firmware from manufacturer, because some operators (AT&T for example) disable GPS function in their OEM Sierra Wireless 881U modems. Of course, you need to solder SIM card holder and a Mini PCI Express connector to the motherboard of your Mini. Also you need some kind of antennas if you plan to use MC8781 modem card internally.
Hope this will help.
Dell Inspiron Mini 12, 1.6 GHz CPU, 1 GB RAM, 40 GB HDD, 3 cell battery, MS Windows Vista.
Want to install internal WWAN modem, replace HDD with SSD or CompactFlash.
P.S. English it is not my native language, so, please, excuse me for its poor quality.