Well, that requires scripting--and I wont bother to give you the exact script cause scripting doesn't work in MP..
What I have done in the past to mimic disentegration--it set the trigger brush to
And then teleports them to a fully black inclosed room some where off to the side of the map.
Then I place a trigger hurt inside of the black box and set it to -1 to start the fall/fade effect.
It's a decent solution--give it a shot.
Today isn't your lucky day....tommorrow isn't looking good either...