Yes, that is possible using VBA and the ClearCase Automation Library (CAL):
http://www-01.ibm.com/support/docview.wss?uid=swg21123249
I created Excel spreadsheets with menus that generate various ClearCase reports. Works great (although slow).
Example:
Set ctObj = CreateObject("ClearCase.ClearTool")
rCode = ctObj("startview " & viewName)
rCode = ctObj("mount " & pvobTag)
rCode = ctObj("cd M:" & viewName & pvobTag)
projectList = Split(ctObj("lsproject -fmt ""%[name]p\n"""), vbCrLf)
...gives you an array with all the projects in your PVOB.
Jozef