What about a Live FX that would gate based on a synced grid (often called a Trance Gate)? The grid would be editable so that you could turn each 'slice' on or off.
Multiple instances of this could be used in an FX Rack so that you could have different processing for different beats/slices. (I know you can do this know in Live 7 with slicing, but this would allow a global effect to be place easily on any clip).