OH! the dissipate anim. ah. ok... um... these are normal anims? or are they custom?
If custom, it's only a matter of having your dead character (lol) rise up, tail, arms, and head limp, weapons hanging, perhas even swinging a little... and then haing him slightly translucent in magos for that anim only. If these are standard anims and your trying to add one... I have no clue. Sorry. :/
(If I had the model and it was rigged properly with the proper skeleton in Milkshape, I'd be glad to do it for you, but as I don't... I can't help you. Sorry. D: