Right now I've coupled the Warlock and Priest spells like this:
[code:1]
Unstable Affliction (1.5s) - Vampiric Touch (1.5s)
Siphon Life (instant) - Vampiric Embrace (instant)
Corruption (instant) - Shadow Word: Pain (instant)
Drain Life (5s channeled) - Mind Flay (3s channeled)
Shadow Bolt (2.5s) - Mind Blast (1.5s)
Shadowburn (instant) - Shadow Word: Death[/code:1]
Besides these I've remapped F1-F12 to heal the priest ( F1-F4 ), warlock ( F5-F8 ) and warlock's pet ( F9-F12 ).

The heals work great, the trouble is that the priest runs out of mana if I keep casting SW:P on every mob I pull with the warlock. Maybe I should stick to healing the warlock giving it endless mana and no downtime?