I've never actually stormed a corruptor in 2.2.1, but a tactic that's worked for me in a number of situations where a lot of aliens are holed up in a single building is to play a little game of peek-a-boo with them.
Turn everyone on multishot reaction-fire (might not work in 2.3 due to the change in RF rules), and post them around the main entrance of the structure. Make sure they're just out of sight; the aliens should have to come out to take shots at anyone. End turn.
One of two things will happen: either the enemies will come out of their hidey hole and get shredded by reaction-fire (Particle Cannons on "Unrestricted Blast" and Plasma Blasters on "Ball" mode may take out several victims at once), or they'll hole up just behind the entrance and wait for you.
If they opt to wait, you just need grenade launchers and stun grenades; march your grenadiers up to the entrance, just far enough that they can put grenades inside, and flood the entry-room with explosions and gas. Everything clustered up to kill you as you come in will be turned into ash or put to sleep. March your grenadiers back out with their remaining TUs and send in one guy to see if anyone's left alive in there. Make sure he's got enough TUs to move back after taking a peek.
If nothing's alive, march on in and clear out any stragglers who didn't join the welcome party. If there's a survivor or two, repeat the procedure until the place is properly sterilized.
