Bleh. Thought I had a clue after noticing a map change from far away when I jammed in a tree... But so far only thing I discovered is how to crash people, which isn't of any help -_-
When you change map, client send a packet that make you load next map. If you are too far away, you receive packet saying so, and the client send a move packet that make you walk there first, so sending the map switch packet from anywhere just make you walk to it if you're in the same map, or if not, do nothing.
Then, I thought there might be a way to connect to the housing channel with your backpack or whathever merchanding stuff. When you change channel / cc, client send a disconnection packet, then a connection request for your character to that channel. After disconnection packet is sent, client go crazy and even crash your comp if nothing else is sent. But, sending the connection packet somewhat just bring me back to the login screen. I guess I'm missing a step :S
Anyways, proper teleport for merchanding probably doesn't involve housing. I tried sending map-switch packet and return coupon packet, none of these worked so far >.< Only thing I managed is to get a flier in my inventory from anywhere xD
Something interesting tho is how when you feed ego, client send a packet with a string containing some xml instruction about feed which item, then send some xml about result...