This may be the case that you failed, and not sure how long ago you did this, but just wanted to point out that SE changed Dynamis bosses so pet's don't despawn at pop anymore.
Just did dyna-bastok boss the other day on BST and had no issues with pet depopping when boss was popped.Edited, Aug 21st 2012 7:10am by EternalEmptiness
Yeah, this was quite a few months ago. The level cap was 99 at the time, but it's been the cap for a while now. I vaguely remember SE patching that, but I wasn't sure.
That should make the beginning of the fight a bit easier. You would still need to get some hate on the two helper NMs, snarl, and quickly switch to the main NM so that you're ready to interrupt him when he readies Death.
Lyonheart of Lakshmi
lvl 99 NIN WAR BST THF BLM SCH WHM
1/467 on signed HQ Weskit!!!