The dominant idea for me is to record the explosion and replay it in reverse to recombine the object. Recording the animation within UnrealEd is the solution I would seek and Sequencer & the Replay System are what come to mind.
If all else failed, I would devise a means to record and replay the animation myself by exploding the object and tracking each of the fragments Transforms {Location,Rotation,Scale} each frame in a array of arrays.
The other option is to record the explosion animation in 3rd party editor export to skeletal mesh.