I have Plague Strike, Icy Touch, Pestilence, and Death Strike all macro'd with Rune Strike. I never have to worry about runic power this way and mobs stay glued to me. I open with Death and Decay, IT/PS and Pestilence to everyone and I have no issues whatsoever with aggro.

I guess you could make it into a castsequence but I prefer manual control for the DK.