Unfortunately, all I can think of is for you to create a sorting table, call it tblSort, with the sort order you want and a sort number, then link tblSort with your data and sort the query on the sort number.
I can give you details if you let me know what your table name is and the name of the field on which you want to sort. I am assuming that your data is not really A, a, B, etc, but more like Adam, ant, Betty, bee, Carl, etc.