In Access 2002 or later, I believe you can use the (new) AddItem method
of the combo box to do this. This approach is limited, however. In all
versions since Access 97 (at least), you can specify a user-defined
function as the control's RowSourceType, and let that function provide
the items for the list rows and columns. The function must have a
special format. See the help file entry for "RowSourceType Property
(User-Defined Function) - Code Argument Values" for information on what
this function must look like.