Thats funny you brought this up.
I just bitched at the owner of the gym I go to that they don't have a glute ham raise. He said he is going to look for one, but in the meantime he had an exercise to show me that would be comparable.
Then he proceeded to hop on the lat pulldown pad and do those exact movements.
It was a little odd as the pad for your ass on there is skinny. Hard to get your legs situated on there, but the lat pulldown I have at home works perfectly, nice wide pad to use for the knees.
And I tried these for the last 2 weeks, even without weight, they are a killer. lol