Originally Posted by Reset
so, if i put the backdoor.sh line there it should work?
If you mean modifying the rcS file, then yes, of course. You can put any call to a script file into it, as long as the script is accessible at run-time. (I.e. not in the root directory, but the SD card or non-system onboard-memory.)
Otherwise I don't think there's too much you can do.
But if there is no backdoor at all, I don't think you can modify the live rcS file.
You could modify the fs.tgz file, though. That should be simple enough, unpack it, modify, pack again.
Then do a simple firmware upgrade. That should work fine - unless you break something (be careful when editing these files - keep the new-line characters intact. Unix/Linux and Windows use different new-lines, which can easily break the script).