Fantastic - based by your response I'm guessing that the scanner is working? If so then that's great!!
More explanation of the commands: I assume that when hplip is installed during the VL installation it puts the hplip daemon script in the standard /etc/rc.d. The permission change (chmod a+x /etc/rc.d/rc.hplip) simply made the hplip script executable so it COULD be started, afterwhich the user needs to start the daemon (via the script) by issuing the 'start' switch.
If upon reboot the hplip daemon is not started then adding that line (i.e. /etc/rc.d/rc.hplip start) to the end of /etc/rc.d/rc.local will make that process automatically start upon boot.