Hmm that's way off then. Although I'm good at following directions, I have almost no clue how to do this. I know the dd commands can be dangerous though, so I'll wait for instructions instead of blindly trying things randomly. What else should I try to get this?
the modem.bin might be on the other block, so try
adb shell su -c "dd if=/dev/block/mmcblk0p12 of=/sdcard/modem.bin bs=4096"