Build GBA SP headphone adapter

Does anyone have the wiring for a GBA SP headphone adapter? If I understand correctly, the adapter fits on the charging port? If so, I have an extra charger that I can donate to the project. It seems like one could just get a headphones jack from RadioShack and solder it to the cord. Correct me if I'm wrong.

I used to have one of those adapters, but it broke down (Made in China TM power).
Since the cord was about 1CM long, it was not going to be reusable to I trashed it.

I still have the earphones that shipped with it, but they tended to hurt my ears anyways (they are too big).

A charger cable might not connect the headphone out pins and thus have nothing to solder to. Looking at the pinout, you have to connect headphone detect or it won't disable the internal speaker and output anything. Regarding quality, if you get a cheap cord from any country it won't last.