There's a pattern actually, its something like:

rock shards
jump
rock shards
5-15 seconds later, lunge and grab


So as an OT you can simply wait 5 seconds after the 2nd rock shards, taunt, and then YOU will be grabbed. I've actually run 3 different instances at once many times, where 2 have my shamans DPSing and one has my pally tanking, if you follow the above pattern you barely have to pay attention as an OT since you only tank for about 3-10 seconds every minute.