WARNING: Mild Bleach Spoilers! (Kind of...)

So first, I would like to know if it would be against a copy-write or anything, if I used voices from the anime, saying "Bonkai". Like Ichigo or Byakuya Kuchiki?

Secondly, I was wondering if anybody is interested in making this? I don't think it'd be too hard, but I don't really know, as I have no experience in the new CK. (And very little in past Construction Sets)

I said I thought it'd be fairly easy, because Ichigo's bonkai would basically summon a robe, sword, and increase attack speed (theres already a shout that increases attack speed).
Byakuya's bonkai could simply summon a few creatures, which would appear as the tiny blades/leaves, or have a cast (like the spray fire spell, but at longer range)
Toshiro Hitsugaya's would summon an Ice Dragon (re-skinned, would be the cheapist/fastest/easiest way I think)
I think most of the work would be on creating new models and effects. I know theres a Bleach Overhaul mod, so if they gave permission to use some of the models they have, that would take out some of the work.

So is there any interest in this? If it is against a copy-write or something, to use their voices, then this instantly loses a lot of interest I imagine :\ So hopefully it's okay to take the voice actor's saying 'bonkai'

You mean 'Bankai' =P

I don't think there would be any problem using the voice clip, it's only a small part of the anime and shouldn't cause any fuss. It's not like you're making money from it or anything, and you're not using assets from a game.