This requires hand coding to accomplish.
you would need to add select list to the checkout form to select the carrier, and a select list to select the service, and store the selected values in session variables.
On the confirm page, you would need to add a server behavior for each of the available shipping services.
in the eCart object crete a shipping rule to for each server and trigger the one to use based on the selected service session.
if you need help implementing this, we can assist you in a premiere support appointment:
http://www.webassist.com/premier_request.php