allow custom options to be modifed via a hook ..

This seems like a useful feature and can be structured similar to buildAmount hook. We allow hooks to modify the option array so they can use a diifferent table if needed to populate the option array. For ease of implementation we'll keep the UI the same, so folks will need to create at least one dummy element and then override it in the hook

http://forum.civicrm.org/index.php/topic,6394.0.html
http://forum.civicrm.org/index.php/topic,6477.0.html