Unfortunately I don't think the rules actually tells you how to do it.
Make sure all the ships are of a type that can be NPC-piloted. Then, set yourself as pilot of the ships and enter the cockpit of one of them that you want to fly. Then, go to "Manage Piloted Ships" and select the other ships of the squadron, and tell them to "Set NPC Controlled". Then they should fly in formation with you.
From memory I'm pretty sure that's right, someone correct me if I'm wrong.