The commands urpmi.addmedia, urpmi.removemedia, urpmi.update and urpmi are precisely what you are looking for. Have a peek at the man pages for these commands and at the file /etc/urpmi/urpmi.cfg on your system for more information.
HINT: You want to add a new media for your extracted directories of RPMS and possibly remove the entries for the CDs --------------------------------------------------------------------------------------------------------------------- the question of course is will the cli tool also fix the gui tool (ie does the package manager get its data from the urpmi data?) HINT response: exactly my plans i just don't want to break the dep solve function ie i install the downloaded foo rpm and it pulls the barlib rpm from the "hive" (asking for the correct media)