Definately possible - my (old) guild's first kill was done with a paladin and a holy priest (since the resto druid disconnected right before an infernal dropped onto him), and no shadow priests.
Both of the healers were fairly poorly geared - the paladin had approx 1400 healing, while the priest had around 1200. Our tank was a warrior (crushings in phase 2) in blues and 2-3 kara epics, a bit over 15k raidbuffed hp, if i remember correctly.
Although we did get very lucky with infernal spawns and had to move only once during he fight, I'd say its definately doable
