As far is i know the teleport hack is memory based. You don't need to disassemble the client for that. From what i've seen there are three different locations in memory that store your xyz position. Only one of them visually affects your character. But you should change all three of them nonetheless. Then you have to use a certain skill to sync your character so that it doesn't pop back to its 'original' location.
Here's a list of skills you can use to sync your character when you changed its location: