Does anyone know if ally spirits can be chanelled? If they can, how do the rules differ from normal channelling?

The general thought is that they cannot be channeled, nor can free spirits or any non summoned spirit.

IMO, Only spirits that owe services can be Channeled.

Once channeled, the spirit owes you no more services no matter how many you had remaining.

As a GM, I would allow a player to channel an ally spirit or free spirit bound to him/her with the understanding that the spirit would be free of its servitude once the channeling was complete.

Some disagree. usually the ones who also bring up "What if a bound free spirit is channeled?"

[/edit] personally, I allow Ally and bound Free SPirits to be Channeled without their freedom being granted at the end. Others disagree.

How do using the powers work? Can you simultanseously sustain movement and conceal, can you only sustain one at a time, is there any penalty for sustaining powers?

You treat the channeler as the spirit with a force equal to the spirit. Whatever limitations on powers the spirit had, the channeler now has.

Thinking about it a little more, how about this.

after the channeling letting the ally test to go free as if the character had taken deadly (i think that one way for it to happen). 2 chances if the charatcer does actually take deadly from the channeling

And with (bound) free spirits, allow the Channeler a another attempt to bind it again if they want it. if after taking the the D Stun from the Channeling they can still rebind the Spirit then they are powerfull enough to keep it hanging around in my book.

Just some ideas.

I don't think, power-wise, it should be a big deal to allow channelling of Ally spirits. I mean, compared to most other spirits, you wouldn't get a whole lot of powers. You could Sense Link with yourself... uhhh, how about telepathic communication with yourself? Immunity to Normal Weapons would be usefull, but that's about it.

Free spirits are a whole other argument. They could really get out of hand, power-wise. Allowing a player to channel something with some of those cool Free Spirit abilities... like after channelling it, going to its Personal Domain and whopping hoop... or using its wealth power for quick cash... Not game breaking, maybe, but on top of its other, normal spirit abilities... One hell of a powerful channelling.

However, wouldn't free spirits either demand something in return (treat as Dragons for rules on dealing with them).
Either that, or you're talking a bound free spirit, in which case you're only annoying it more in preparation for when it does eventually break free. Maybe it won't stop at just trying to kill you then, maybe it'll keep you alive, but kill your friends, or otherwise go for the life destroying approach before finally destroying your life (in a more terminal sense).

Then again, maybe it secretly gets a kick out of it?

You can't channel a free spirit unless it's bound, because until then it doesn't owe you any services. Even once it's bound, it still technically doesn't owe you anything, it's just obeying you.

It would be interesting to see if a free Loa spirit would agree to Possess someone, though.