userService.cfc should return a struct with two properties.
The first should be the destination of the data (which combo box).
The second should be the query recordset.
Then when you receive the resultEvent to
handleReturnedUserResult, you'll need to check the message body's
destination property to determine what combobox in flex should have
its dataProvider set. You can do this using if else statements or
some sort of dynamic evaluation.