It's been a while, but I think what I did for this one was keep Snow as a Sentinel and Hope as a medic for the entire battle, and then had Vanille alternate between whatever roles were necessary. Or it may have been Snow and Fang, both as Sentinels the entire time. In any case, two of my party members never ever switched roles when changing Paradigms. It was a slow fight.

Vanille's magic stat affects Death's success rate, so it's good to have a maxed out Marlboro Wand, which has an ability that improves the success rate of Saboteur abilities. Also, Snow has a nifty weapon (I can't recall the name) with the ability Improved Guard II that's worthwhile in situations where you never take him out of the Sentinel role.