Anyone?
??.....

Torque converter is not sealed. The gearbox fluid is circulated through it by the pump in the gearbox.
I would first disconnect the cooler hoses at the gearbox and the radiator. Thoroughly blow these through with an airline to purge them of any water. Blow through the cooler part of the radiator, again, to remove any water. Use something like an old killaspray to purge these with fresh ATF, if possible.
Drop the sumps on the gearbox and discard the fluid, reassemble and refill.
As an extra precaution when refilling with the engine running I would leave off the return hose from the cooler (can't remember which one this is) until it has bled off a little fluid before stopping and reconnecting it, just to be on the safe side.
I'm sure a
tiny amount of water will probably do no harm and get "breathed" out of the box as soon as it exceeds boiling point but any significant amount of water will wreck it, so it is vital that the above is done before starting the engine IMHO.
I would also suggest a second fluid change once the car has been driven and found to be OK, just to make sure.
Kevin