From ADS2011 version onwards archived libraries are available at: C:\agilent\ADS2011_10\oalibs\componentLib where C:\Agilent is the installation directory of your respective ADS version which in this case is 2011_10.
How these libraries needs to be included in ADS2011 workspaces:
1. Open the workspace in which you want to add the vendor component library or PDK.
2. From Main ADS window, go to DesignKits->Manage Favourite Design Kits
3. In the pop widnow, select Add Zipped Kit and browse to the location mentioned above….e.g. Passive SMT components can be found in RF_Passive_SMT_Vendor_kit.7z archived file
4. Click on Open and select location for Unzip….
5. I recommend to use a central place/directory to keep these unarchived libraries so that everybody can use it in their work.
6. Once it is unarchived, ADS will ask for adding it in current workspace, select Yes.
7. Now if you go to library manager it will show all the components under Read Only Libraries. You can select the component->Right Click and select Place Component to place it in your schematic.
8. Next time you are creating a workspace this library will appear in the Favourite list and you can add it to your workspace.
See the attached video for more clarity….