As far as I can tell there is only one other sorority on that campus and it is not NPC affiliated.
First of all you need to determine if there are campus restrictions to bringing in a national 'social' sorority. If not, you will probably need to get approval from the campus administration to start the extension process.
As you begin those inquiries, you can start getting information from the NPC itself by visiting
http://www.npcwomen.org/college/c_ex..._resources.php and download materials with information.