I doubt this is possible, sadly, because combat is so random in the Batman games. I'm trying to finish up the last combat challenge in Arkham Asylum and was trying to get the perfect freeflow achieve and finally got it. It would be possible to record a perfect freeflow, but it would be so random trying to get it to work. Basically the exact same events would have to happen as when it was recorded.
My advice is just start practicing and get good at stringing together the first half of the combo and then work on the latter half. You'll get it mate!
