Win32::OLE::Const outputs warnings for the following code:

>perl -wlE "use Win32::OLE::Const 'Some Madeup Library'; print 'All is
+ well'"
No type library matching "Some Madeup Library" found at -e line 1
Win32::OLE(0.1709): GetOleTypeLibObject() Not a Win32::OLE::TypeLib ob
+ject at ...
[download]

... so you will have to look through the Microsoft documentation on Excel to find out what type library to use when.