Yes, you can do this, but you will need to do some hand coding and it is not supported.
It will require creating the select list on the checkout page.
add a hidden form element on the confirm page to capture the value from the select list.
Add a set session value server behavior on the confirm page to capture the value from the select list.
Add if statements around the local checkout code on the confirm page so it will only be processed if the Pickup form store option was selected.
add an if statement around the UPS Shipping code on the confirm page so it will trigger if the normal shipping option is selected.
create a new shipping rule in eCart for the courier shipping option. Set the trigger to be based on the session variable that was created.
You will need to be comfortable with writing PHP if statements to be able to get this to work.