Nah once it's past the event horizon it's a done deal. I imagine something like orbiting a pulsar and black hole around one another and taking advantage of the electromagnetic stream. Just align the pulsars pole with the black hole, or stretch the thing into a bell like shape (somehow) so the heavy end is pulled towards the hole always, rotate them somewhere in the realm of light speed (so the attraction is counteracted by the rotational speed) and go nuts.
How to implement this? silently screams
Since one of the variables involved in determining the event horizon is gravity, it is my perhaps mistaken expectation that the interaction of two event horizons upon each other would impact the location of each.
Since the event horizon is that point where nothing, not even light can escape, and since this can be visualized as a circle or sphere, the interaction would have that event horizon grow ever smaller as the conflicting gravity forces draw upon each other. This , in turn, would cause matter and energy to spew forth at great velocity until the event horizon stabilizes once again - the merging of the two.
Well that is what I think might happen.
Your subsequent idea sounds more interesting. How to implement this? Lets just say that the tractor forces involved would be beyond epic. ;c)
I (think) they just kinda merge together, like two drops of oil in water, and yes the last thought would indeed be epic, the problem would be tethering something in between that could handle the insane blast of beyond energetic particles, and the tidal forces. hahaha.
Sounds improbable, but not impossible.