If you have access to VBScript code that utilizes the module, then the road will be pretty easy. The Win32::OLE module will allow you to perform a CreateObject or GetObject just like you would in VB/VBS, and from there the syntax is very similiar in that you are calling the same object methods you would from any other language. You can google 'perl use Win32::OLE' and get some idea of where to go, too.
If you don't have a VBScript example, then you need to figure out what the ProgID is for the object. You can find this by using OLEView or just sifting through the registry (usually a Find for the dll filename in RegEdit will get you to the ProgID quickly). OLEView is handier, becaude you can get a view of the exposed methods and properties the DLL makes available.
If you could provide the name of the DLL and the developer, then I could give you a straighter path.