Use 3 tanks.
or use the DK on adds/drakes.
The only way to reliably pick up the adds is to have an AoE already there (conc or DnD).
We personally went with 3 tanks for the encounter and 2 healers. Even then, I would say a DK or pally is your best choice for the adds. The only other thing I can think of is to have a holy pally conc the portal with RF up and then you can TC + SW them off him.