Hi,
I think what you are asking is for the list to do an incremental search as the user types in values, so that entering 'br' finds all list values starting with 'br'*
Sorry, but amoung the 4 key differences between combos and lists is that functionality (others being size, only-from-list, and multiple selections). To move through the list, the user can keep using the starting letter to iterate through the values (eg first 'b' gets first entry starting with 'b', 2nd 'b' gets second & so on).
If you needed to, you could have a 'search' field which the user enters data to filter the list as they type. This would need some minor coding, to requery the list as the search field is populated.
Cheers