I tried opening the DialogueEditor to see what actions and conditions they used but I received an error saying that I need developer rights to open the GenericKeyWords.lsx. Was this an intended error or is it possible to unpack the main campaign dialogue using lstools?
Yes it is possible by unpack the main.PAK and copy the "Keywords" Folder to mods/main/story. Now you can open "CYS_Walter.lsx", but read only. I think the Developer Rights Error is because the Engine wants to open the Keywords in the .PAK Files.
I think Larian do the teleport by seting an FLAG to the Party.