Normally, I would not look into something like this, but the FCC rules that govern FM modulation are beyond inane and dictated by private interest groups.
So if own an XM Inno there is a great firmware mod that allows you to use the FM modulator in your home cradle.
0) to avoid bricking your Inno you need to update the firmware to v2.11 (currently it is the latest firmware)
1) Download: firmware
2) Plug your Inno into it’s home cradle with the AC on
3) Connect the the USB cable to your computer
4) Place the file into your Inno’s root directory
5) Safely remove hardware
6) Disconnect the USB (leaving the Inno in the home cradle)
7) It will scan/reboot/done
-It will now have a Samsung logo and FM modulate in the home cradle
– You will need to turn on FM modulation every time it restarts.