When I run it on my Titan (on hard) I make sure someone distracts boomers with a bubble and then I wait on the rock on the right side. Once I get on the rock I let everyone know to shoot rockets and as soon as I see them I jump up. The timing is hard but after a while it's really easy. I'd go for 3 hits using RT while running coward. Rains blow perk increases melee attack speed so that always helps.