The way the Components dialog box works is that it actually looks inside a folder to see if any files there it can display.
To get a better picture, here is what you have to do in a Windows computer:
Computer>Hard drive(or where SU was installed)>Google> Google sketch up [your version]>Components
Thats where SU stores its components, if you want an extra pack look at the guy above or wait until Google makes a v7. Personally I just put any models that I like into this folder.
Some of you might not know is that now the dialog box actually links to the 3-D warehouse, so whatever you search in that search box there will come up the same in the warehouse dialog box. Simply its just a faster way to surf the warehouse without taking up so much space when you don't want it to.
Yea its messed I know.