There is a registry setting that allows you to configure which nodes are displayed.
Check out the Customization Guide, and look for "Show/Hide Nodes in WorkSite Explorer".
Basically the key is in HKEY_LM\Software\Interwoven\WorkSite\8.0\Common\Options
A DWORD with the name "Show Explorer Nodes Mask"
and set the value based on what you want to display where;