Using User-Defined function in SQL

Hi All

I am querying an Access database using ADO in Excel VBA.

Is it possible to use a user-defined function in my SQL command text? I know I could house the UDF in Access and then set-up the query there, and then use excel to run that existing query, but I wonder if it is possible somehow to actually use the user-defined function directly in my SQL string in my Excel VBA sub-routine.

My user-defined function is just basicaly a long Select Case statement, so I could use a really long IIf statement in my SQL string but the UDF is so much tidier.

Any ideas?

Thanks
Jon