Try something like the below script as a logon script.
It is a mix of scripts from the following pages
http://blogs.msdn.com/brijs/archive/2009/05/06/remove-all-pst-from-the-outlook-mailbox-using-vbscript.aspx
http://www.visualbasicscript.com/m44947.aspx
Set objOL = CreateObject("Outlook.Application")
Set objFolders = objOL.Session.Folders
For j = objFolders.Count To 1 Step -1
Set objFolder = objFolders.Item(j)
If (InStr(1, objFolder.Name, "Mailbox") = 0) And (InStr(1, objFolder.Name, "Public Folders") = 0) Then
WScript.Echo objFolder.Name
WScript.Echo GetPSTPath(objFolder.storeid)
End If
Next
Function GetPSTPath(input)
For i = 1 To Len(input) Step 2
strSubString = Mid(input,i,2)
If Not strSubString = "00" Then
strPath = strPath & ChrW("&H" & strSubString)
End If
Next
Select Case True
Case InStr(strPath,":\") > 0
GetPSTPath = Mid(strPath,InStr(strPath,":\")-1)
Case InStr(strPath,"\\") > 0
GetPSTPath = Mid(strPath,InStr(strPath,"\\"))
End Select
End Function