Where to attach the wires to the iPAQ mainboard:
Originally, I put some flat stiff wires in routed past the battery and around the case:
The circuit used a transistor to convert the 3v logic to 5v and then a MAX232 for converting that to the RS232 levels:
I then put it on a veroboard:
Later on, I put a mini-minijack in the side of the back case and connect it with enameled wire. I'll take some photos of that one day.