Okay, I've seen a lot of posts say that the only way to get into the T'rang restricted area is to kill the T'rang.And this simply is not true. It takes a bit of patience, but it is very easy to repeatedly go into and through the "restricted areas" without laying a finger on the T'rang or making them hostile.
I read about it in a post in this forum a while back, but it doesn't seem to have been passed along enough. The basic idea is that you enter combat mode yourself, before going into the restricted area. I usually walk until one of the guys says 'Stand back!' Then click on the battle icon, select run, and okay, and then run past them. It might take a try or to at first, but it's very easy to run past them. By the time your run bar runs out and you exit combat, you should be past the T'rang.
One of the restricted areas is a bit trickier, where you have to enter in the 3-digit code to open the door (after turning off the gas). But the basic idea is the same, using false combat mode. Once inside this area, you can find a weapon in the very center, surrounded by a group of T'rang. Best strategy? Enter false combat mode, pick up the item DURING combat mode, then run away as fast as posible. These strategies have always worked for me.
Alternatively, you can try to camp until you engage in a battle near the T'rang that will cause them to run away. This in my opinion is much more of a hassle, but is still possible.
IMO, Sirtech planned it this way all along. Turning on/off the gas is not an issue if you've defeated the T'rang. But if you try the false combat method, forgetting to turn off the gas will force you into combat. So why include it, unless they planned on you using the false combat mode?
Really, this is not any trickier than making characters unconscious to enter areas, and Sirtech knew about that quite well, as it even has some of them comment that "You must've gotten me unconscious..."
Anyway, I just wanted to pass that along, in case some maniac gamers out there wanted to get and do everything, without upsetting the T'rang.
Actually haven't play FO2...You don't enter the code in Fake Combat mode. It's tricky, but entirely possible to exit false combat mode after sneaking behind the T'rang guards, and they will not observe you. Why? Well, I dunno, but for whatever reason, generally, they will not notice you. Which gives you time to enter in the code. Just don't move after doing so... you have to then return to false combat mode to enter the next room. This is why you don't turn the gas off, your party gets frozen and then they catch you and turn hostile.
I don't recall exactly, but I think the best trick is to enter false combat mode, run up to where you enter the code, and then exit false combat mode. I believe this was more effective at not disturbing the guards then just waiting for the run meter to run out. Definitely save beforehand, you might have to try a couple of times.