just use the AexAPEdit.exe, which is located outside of the Inventory Solution, in the NSCAP\bin\win32\x86 directory to edit the existing auditpls.ini (which is in the same directory but one level deeper, in the Inventory Solution folder).
So runt he aexapedit.exe, and the use the 'file -> open' to select the correct file (the one listed above) and edit it as you need, meaning add the file mask *.ost, and make sure the 'include unknown' box is checked.