My players were interested in forming a Psyker Battle Squad with each other, which I was going to house rule together, and I'd be happy to post in my house rules once I get them together.

Beyond that, though, would you guys let your players take Psyker talents ( Psyrating, most importantly ) as an Elite Advance? Would a Dark Pact be the only way to get Psychic powers?

I was thinking that over-dosing on Spook, longterm exposure to the Warp, Dak Pacts, psychic implants, wearing psychically tuned equipment ( to replicate the power ), daemonic possession, or intense emotional stress could push them on. I don't really want to do the Nascent Psyker advance, though, because it isn't really the Psyker Battle Squad feel I want.

Majorly I was thinking that a Psyker Battle Squad would make the most sense ( if you guys know Imperial Guard, that is ) because they aren't inherently powerful Psykers by themselves. Your input would be really nice, but if not I might just make a Psyker Battle Squad campaign after this.

Rules I was thinking is that they divide their Minors Powers amongst each of them ( serving as a single Psyker ) and can use their minor powers on their own, so long as they are all there ( -1 to the roll for every character in the choir not there. ) All major Powers require the whole squad, and one person is the caster, with each of them adding +1 to the power roll. It will be a powerful unit, but only one major power per turn, and they need to spend their XP together to increase the Psirating of the squad, not themselves. ( They will never be above Psi-rating 1, individually, basically. )

Well if your whole goal is to allow this and make it work, I think the simplest way to get it started would be to allow them to take psy ratings as an elite advance (stressing the increased XP cost maybe) as you described. If your cool with them doing this, I say go for it! As a GM myself I wouldn't let a player take psy rating as an elite advance but then again, they wouldn't be taking it for the purpose you would be describing.

As far as mechanics go your going to want to find some way to give the low WP chars a reason to ever be the manifestor of a power, maybe when one of them uses a major power they can't manifest another one for 1d5 rounds? As you said they aren't powerful psychers and the stress of this sorta "battle meld" is probably going to get to them, especially when they are the one channeling all the power.

The problem with this is that psykers are supposed to go to Terra to get sanctioned. If they don't do this, they're considered rogue and get a nice pyre by the next witch hunter.

If you find a way around that, search the forums. I believe there recently was a thread about psychic choirs...

Thanks for the help! It took me a bit, but I found the other thread. I found it easier using the word "Choir" than "Psychic choir" because of all the other use of the word psychic, and I posted my own mechanic for it in the House Rules section so we'll see how it goes.

Much obliged everyone! Now we just gotta work on how Nascent Psykers work with them...