I'm a Healer. (Pretty much the hardest role in that fight) And I find it very simple and fun, I got my relics for both WHM and SCH by shouting for groups. Just create the party yourself, and do a bunch of runs. Don't ever expect to win with the first group. You WILL have to weed out the ones that keep getting hit, just keep replacing all the ones that keep getting hit until you have a party that can dodge. Then win, GG.

It IS an all day thing, but don't give up, you'll eventually get a competent group. ^^