How to fill Active X Combo Box on Visio Page

I have a Visio model that maps Shapes to an Excel External Data

I would like to populate a Combo Box on the Visio Page with data from
an Excel Range in the same Excel Workbook. But do not know how to do
the mapping.

Any ideas on how to adjust the Combo Box data source properties
directly using the Properties Window or indirectly through VBA?