How do you do emergency stops at highway speed?

[MarkyPancake]

I apply both brakes firmly so as not to skid, front first then rear and then disengage the clutch when I'm about to stop.

If you disengage the clutch too early the rear wheel will lock up due to the hard braking and this will make the situation more dangerous than it already is.

[JustJames]

I always practice quick stop at around 50mph on empty street (after midnight). The pratice is to get used to with habbit of grabing the front with smothness and apply rear brake not too hard to make the bike skid, not just only to STOP.
IMHO, The very important thing to do quick stop is to not panicing or exciting to cause you to grap the front brake too hard or stump or rear brake pedal.