Do you have the two possible destinations in a db table? If so you could have the user fill in a form with their location then choose the destination from a select list on the form. When the page is submitted to itself it will post the id of the selected destination, you can then have another recordset that will select that destination from the db. You would then use this recordsets bindings for the destination location within the Maps interface.
This is not something that we have a specific guide for but it could be done like described above if the destinations are in a table. Let us know if you have any questions about this and we will be glad to help you with whatever we can.
