I find sometimes its easier to add components and part numbers directly into to Access database especially if you need to add a lot of part numbers or a whole new MFG. The path to the database on my XP machine is \My Documents\Acade 2012\AeData\PLC. Then open the ace_plc.mdb and on the left are all the tables. You will also see in the path \My Documents\Acade 2012\AeData\Catalog the default_cat.mdb this is where MFG part#'s are stored based on the family ie CR, LT, SS .... you will also see the footprint_lookup.mdb this is where Autocad looks at the part # then decides which DWG to use for the footprint.
All the schematic and footprint DWG's are located here C:\Documents and Settings\All Users\Documents\Autodesk\Acade 2011\Libs.
For me looking at these databases really helped me understand how the whole catalog/footprint features of ACADE work.