Also if you start the quest ghost town gun fight and side with goodsprings you can still get the quest and also complete Eddies quests in the prison....all you have to do is DO NOT FIRE ON THE POWDER GANGERS...you WILL get a slight negative karma hit. but if you just loot some PG clothes you can still get into the prison with no problem....a bit longer but thats how i did it.
There is an alternative that does not require you to wear the PG's silly p.j.'s AND kill them all before the NCR's takeover of the prison:
You can finish Ghost Town Gunfight, siding with Goodsprings and helping during the shootout (the PG's will hate you, but not so much). That's what I did, after recruiting all of Goodspring's possible allies, and crouching near a crate for stability while shooting (perhaps this helped with stealth as well, but I doubt it).
Then retake Primm from the PG's (if possible, try to remain relatively stealthy during Primm's takeover).
Head towards NCRCF to find Meyers.
The trick: don't get seen/caught shooting the Powder Gangers (and don't get a reputation that's too low with them before attacking NCRCF). I didn't shy away from shooting at the PG stragglers along my way, but I was always careful to be discreet about my own special kind of justice. You'll cross a few during your travels between Goodsprings, Primm and NCRCF, and if you are modestly stealthy, the PG's won't know who or what hit them.
Snipe the tower guards and the roaming PG's hanging in the NCRCF courtyard from the hills just west of the prison entrance. Far enough so that if you miss a shot, they won't know where it comes from (quite far, like the top of the highest hills). Take your time, place your headshots well and you won't have any problems. Once most of them have been dispatched (I couldn't reach the tower guards on the East Side, I still had a "young" and ill-equipped level 7 character (used a silenced Varmint Rifle for the NCRCF clean-up, no scope)), proceed in the prison itself and tell Meyers to leave. The PG's won't be hostile (at that point, they didn't like me but they didn't hate me too much... yet), so just shoot the surviving PG's in the "living quarters" (closed-up buildings) point blank in the back of the head (again, and this is crucial, silently and stealthily). Shoot everybody at NCRCF with the exception of Eddie, of course and (little suggestion) spare the "medic" sitting on the first floor of Eddie's "new HQ" in the prison. Once you reach Eddie, he'll give you work thinking his men are all still alive and well.
Of course, it takes a while, but I think it's very rewarding to be Justice's Silent Executioner for this particular takeover. Then you can do Eddie's dirty work AND retake the prison with the NCR. There were, of course, only two people for the NCR soldiers to kill (and I did manage to kill Eddie myself, just for the sake of role play: I wanted him to know who betrayed his sorry bastard's a$$).
Indeed, once Meyers is Primm's Lawman, nag Nash a little. Pull on his heartstrings. Say something along the lines of "If you don't tell me what you know about the impending NCR attack on NCRCF, I'm just going to do it myself". He'll say you've been so helpful to Primm that he'd feel bad for you to get in harm's way (Ha! If he only knew... You
are harm's way), and he'll spill the beans on NCRCF's attack. Go tell Lt. Hayes that you know everything about the attack and want to join in. He'll accept and send you to regroup with his men near NCRCF. Once the soldiers blow up the fence and storm the prison, you'll have a smirk on your face thinking Eddie's about to meet his doom and the NCR won't lose a single soldier in the attack. If you want to kill Eddie yourself, rush to him and let the NCR take care of the medic: because they'll have no other opposition, it'll buy you a few precious seconds to get to the 2nd floor and reconstruct Eddie's smug face with your favorite shotgun of the moment.
Afterwards, the PG's will definitely despise you though.
Jolipinator: even though I got to know the PG's rapist/thieving/murdering side of the story only after caving their faces in, the PG's hatred is probably one of the sweetest rewards I got. These guys don't deserve to be heard, not even for a handful of caps.
(BTW: for precision's sake, this was on hardcoe mode, my character was proficient with guns, obviously, and the Varmint Rifle I used was in top condition during the whole ordeal.)