Colin-
So what are you trying to make? Don't tell me it's an APRS tracker? (isn't that what the HX1 is best for?)
A good example of a piece of code that integrates everything you want except the SD card (and maybe the sensors, not sure what you're looking for) is Trackuino. See http://www.trackuino.org.
Note it doesn't explicitly use a MAX-7, just a gps. I've modified the Trackuino code to explicitly support a MAX-6 (which should be nearly identical to the MAX-7) if you're interested.
Just a thought.
Regards,
Brad
KF7FER