I made a quick example using DT to reduce the jump.
It breaks at around 10 FPS.
http://johnnysix.net/games/scirra/jumpdelta.capx
Just created a variable for "initial jump" , and had the platform behaviour updated each tick :
initialJump*( ( 60 - ( dt * 60 ) ) /60 )
[ Edit- if I was better at maths I would have written something simpler.
60 is just arbitrary, I just picked it 'cos it's a nice number!]