Calling Activex dll

I have a third-party commercial software package with a command interface that is an Activex DLL. It can be called using Visual Basic 6 or Visual Basic for Applications, and also from .NET, I am told. How do I go about calling it from programs in SharpDevelop? In the VBA editor in Microsoft Word, I have to click a box in Tools | References corresponding to the DLL but I cannot see the equivalent in SharpDevelop.