Excel - using Excel VBA to call functions stored in a Delphi COM Add-In

I have a Delphi COM add-in I have created for MS Excel 2002. The add-in
works correctly.

My question: How do I access any functions/procedures I have stored in my
COM add-in from Excel VBA?

The Excel Object Model exposes the ComAddIns collection, but that is about
as far as I can get. I have a standard delphi DLL that does the trick, but I
would prefer to call the functions from the COM add-in if possible.

MSDN reveals a method of doing this with a VB COM add-in - but to do the
same with a Delphi COM add-in remains a mystery.

Any help would be much appreciated.