The fact that you are getting the "Pssst, come over here" (or whatever it is) shows that that critter's script is working. There is no reason why only half of a script would work. The only workaround would be to use a game editor to maybe change the global variable responsible to get the quest. However, that would not force dialog, it would just trigger the next step (to talk to someone else). Wait... Just to be on the safe side, what are the timestamps you have for vctyctyd.gam (data/maps folder), vctyctyd.int and vcprison.int (both in data/scripts folder)? However, now that I think about it, you've got something else going on. I never changed the script for the guard in NCR. So, there is no reason that one should not work for you.