Here is something to remember for a macro when setting up for a warlock:
Mastery, not haste, is the key right now. The higher your mastery, the more damage your ticks are doing. At the current my mastery is set to 118% and I am doing about 180DPS.
Make sure to use felhunter as it does double damage to enemies with DoTs on them.
Once Corruption has been applied, it does not have to be re-applied. This can be done by casting Corruption directly, or using Seed of Corruption. Seed of Corruption with Demon Seed is best because of the multi-seed explosion doing AoE damage on packs.
This leaves Agony, Unstable Affliction, Phantom Singularity and Drain Soul to be managed through the rotation without eating up all the Soul Shards through repeat Unstable Affliction applications.
Additionally having the Grimoire: Felhunter and the Summon DoomGuard go off when it is up and Reap Souls collect at 12 stacks for maximum DPS. Due to the nature of Reap Souls drop rate being kind of random, we would have to set it to a timed event and simply collect when we can.