HX1 APRS Transmitter Hookup Guide
MikeGrusin 
Configuring Trackuino
Out of the box, Trackuino is configured for use on high-altitude balloons, but with a little hacking you can alter it for your own purposes.
There's one change you must make: open the config.h file, and insert your callsign and station ID at line 42. APRS transmits your callsign in every packet; this is a legal requirement.
Another thing you may want to change in the file aprs.cpp is the "symbol" character defined on line 62. This controls what graphical symbol will show up at your location when you're using APRS mapping software or websites. The provided 'O' indicates a balloon, but there are many other symbols available such as '-' for fixed location, 'K' for school, '>' for car, 'Y' for boat, etc. For a complete list, check out the link below.
By default Trackuino sends an APRS packet that includes GPS time, GPS location, altitude, battery voltage, and several temperature sensor values. If you want to build your own APRS packet, you can alter the aprs_send() function in aprs.cpp to remove various sensor values or add your own.
We'll be updating our fork of Trackuino as well.