I don't know if it's that simple... Helena will spawn on a condition that is probably handled in the OnEnter script of the cantina... So you'll have to delete that part from the cantina and edit it into the OnEnter script of Anchorhead / find another way to spawn her.
Admittedly scripting her spawn point outside of the cantina will be fairly easy. But I don't know about the possibility to remove that part from the cantina (So she doesn't spawn twice
). You can try decompiling the OnEnter script of the cantina and removing her spawn part but I'm not sure if that works.