i already fixed step 5 for you in my macro.

pressing alt, ctrl, or shift with that macro will skip Shield and will go straight to a Renew.

Additionally, your warlocks will not cast Corruption when you cast the alt-renew. this is good since you might not want to refresh your Corruptions to save mana. but then again, you are working with several characters, and four corruptions on one mob will probably kill it before you have a chance to refresh the Corruption.

If your priest is shadow, you'll most likely start using vampirice embrace to recover health for all. this is the beauty of having a shadow priest. and, if you spec your locks affliction, having Siphon Life and Drain Life only adds to the ridiculous non-stop grinding/questing, never needing to drink or eat.

if i had your setup, i wouldnt even use a cast sequence, as i believe it is too limiting to my play. i only use modifiers and conditionals in my macros. i'll write out the macro for you if you want, even though the previously stated castsequence macro will work fine.