If you don't want to risk bricking your $300+ gateway, consider these alternatives:
Stock firmware locks down the command line. A patch typically flashes a modified system.bin that re-enables hidden Telnet or SSH services on port 5512 or 22.
Step 1: Hard Reset
Step 2: Enter Recovery Mode
Step 3: Establish TFTP Connection
Step 4: Flash the Patch
Step 5: The First Boot
Some community patches are poorly configured. They might work for 3 hours and then crash into a boot loop, leaving you without internet until you revert to stock firmware (if you remembered to back it up).