That's the right part I was thinking of, but it looks like we have to trace the code a little farther. I don't remember exactly, but there should either be more code a bit further down that deals with the move flag, or it is passed to the Map_Enemy constructor in part 3. I'll have to download the code and take a look tomorrow.
EDIT: A day late, but it ended up being in the Map_Enemy constructor:
you will have to make a quick edit to part 3, changing line 3167 from
to
and then you should just need a script call to set the flag, I think it should be
$game_map.events[ID].move_flag = true
where ID is the ID of the event. Also, the script call will be opposite the flag, so setting it to false will turn the \move flag on, and true will turn it off.