I have recently done an extensive research on the possibility of tweaking "Shared Workspace" task pane for SharePoint and came to conclusion that there is no way of modifying it. I have two reasons to support it :
1) SharePoint 2003 doesn't have "hide features" in its design model. Everything is shown to everyone ,but actions can only be completed by people who have right permissions. Having said this , I think any mechanism to hide features, on the server side, are not seen in SharePoint 2003 architecture. I went through all the registry keys related to office 11.0 in the "HKEY_CURRENT_USER\Software\Microsoft\Office\11.0" and "HKEY_LOCAL_MACHINE\Software\Microsoft\Office\11.0" and I could not find any keys in regards to Disabling/Enabling "Shared Document" workspace features.
2) According to my research on the client side, all office applications (like word, Excel and etc) provide a customizable mechanism to end users to customize their environments, but they DO NOT really provide facilities for administrators to lock things down.The "Shared Workspace" pane is not programmable which means that there is not such a real programmability model to override the task pane behavior.
We might be able to write Macros or leverage Policies (as stated in Office Resource Kit) to disable a task pane completely ,but who wants to take this great collaboration feature away from office ?
Look at this answer by Mike Hernandez who is the program manager of VSTO (Visual Studion Tools for Office) Team:
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=197143&SiteID=1