The way I understood it, Ye Zun was disembodied when he was first trapped inside the pillar. So then travelling to Haixing in energy form was just a matter of a) getting loose of the pillar (and he's working on weakening it's hold via Zhu Jiu's energy collection), and then b) using a portal, same as all the other Dixingren he's been sending to Haixing?