Welcome to Gaia! ::

Before i say anything this was done on the 360 so I am only sure it works on the 360. But I've heard a lot about how it works on the PC and PS3, just nothing on the invincibility glitch for sure.

This is actually pretty simple and there are different ways to do it but here is how i did it.
1. I had no followers at the time.
2. I had the Puppies! perk.
3. I started this with negative karma.

[Easy Negative Karma: Sneak around Rivet City and kill guards, They respawn infinitely]

First off get Dogmeat's Puppy (I had the puppy at the time and I don't know if the original works.) And ask Jericho if he wants to join, He will if you have no other followers, if you do have followers use instructions to get Clover on Jericho.

To get Clover when you ask it will say you have too much followers... Kill Dogmeat's puppy and ask again. This time it should work.

Go get the next puppy, Get your karma up to neutral.

[Easy Positive Karma: Donate money to any church, Give water to Water Beggars.]

Repeat last step on Butch. (Only Available after you have beaten "Trouble On The Homefront")

Again, Get next puppy, Use on Charon, Repeat, Use on Sargent RL-3.

Raise Karma up to good. Get Puppy and use on Star Paladin Cross and Fawkes. Grab one more puppy just so you have him.
You now have all the followers at once.

Near Invincibility Glitch: This actually happens just by using this technique to get all the followers, For me Fawkes survived all my MIRV shots + continuous fire from me and all my followers, with about 5/8 of his health, and RL-3 and Cross survived against his attacks for way longer than expected. Everyone else seemed to be normal health. Results May Vary.

Extra Info: Beat Point Lookout and The Pitt before doing this, they get auto-fired if you go there and it is always a pain in the a** to do this.

And if you don't know their locations, here is a link to the Wiki:Follower Locations

I would suggest turning your difficulty to Very Hard after this, Deathclaws don't even last 3 seconds anyways.

Also so you dont kill all the fun in the game, don't recruit all of them, probably just Butch, Clover, Jericho, and Dogmeat if you still want to recruit more than you should. Using this glitch while also getting temporary followers like Red, Sydney, or Sticky really ruins it after a while, unless you like having the game almost play itself.

Anyways, Have fun!

I might have given some false info. by accident. I just recently learned that followers get higher stats when you level up too. Fawkes apparently gets a shitload of health. And i am at a really high level. I don't think its a glitch.