As far as exporting to XML, that is fairly easy. Look at Books Online at the FOR XML clause.
With regard to importing an XML file, you can use a DataFlow task with the XML file as the input and a SQL table as the destination. You can also just use a stored procedure using a variable to map to the location of the file and then use sp_preparexmldocument and sp_unpreparexmldocument stored procedures within your stored procedure.
Hope that this helps...thanks.
Chris