In the case where you are designing an set of COM interfaces and implementing a server to support them, you need to make a complete implementation in Lisp. This allows several Automation interfaces to be implemented by a single class and also supports dual interfaces.
The implementation defines an appropriate class, inheriting from the class standard-i-dispatch to obtain an implementation of the COM interface i-dispatch. This implementation of i-dispatch will automatically invoke the appropriate COM method.
For dual interfaces, the methods should be defined in the same way as described for COM interfaces in Implementing COM interfaces in Lisp.
For dispinterfaces , the methods should be implemented using the macro define-dispinterface-method or by a specialized method of the generic function com-object-dispinterface-invoke.
To implement an Automation interface in Lisp with standard-i-dispatch, you need the following:
LispWorks COM/Automation User Guide and Reference Manual - 19 Dec 2011