Function Libraries

Can I create function libraries (COM like) in C# and call them in MS Access or MS Excel?

http://msdn.microsoft.com/en-us/vs2005/aa718673.aspx
Visual Studio Tools for Office.

Thanks Frogman but this is what I was looking for:

http://blogs.gotdotnet.com/heaths/ar...09/391358.aspx

Alright, wasn't entirely clear as any office question is wont to be.