I don't have my PW-3 open, but I do have my KT-2 open.
I'll take a look for that on the KT-2.
Someone with their Voyage open also please take a look for that part outline (don't count on the silk screen to label it).
= = = =
Note:
That USB buss to the SIM card may only be accessible from the 3G modem/radio (also a complete ARM SoC system, like the Kindle itself).
Translation:
Those will only go to the pads for the PCI-e card connector in the upper left of your photo.
And since you don't have a 3G, PW-3 (neither do I), then we can't use AT commands to see if we can access it from the Kindle (through the modem/radio).
Hmm...
But jumping the USB buss
**to** the 3G modem/radio to the USB buss leads
**from** the 3G modem/radio to those of the SIM card on the non-3G Kindles might make that storage available.
For the people complaining that the serial port pads are too small to solder to, just wait until they try soldering jumpers to those PCI-e pads.