The
manual for the kindle cell modem includes a full pinout on pages 9 & 10, and just enough information (on page 11) to figure out that the connector it's using is a 50-pin Molex SlimStack™ (
Receptacle,
plug)
Putting that all together, gets us this:
I haven't tested that at all though. I'll leave it to someone with a spare kindle since I'm not especially keen on breaking mine.