LOL, ok.
Start with a white undercoat.
I used the old
GW paints, so the skin is Catachan Green and I used Bestial Brown, Scorched Brown, Khemri Brown and Enchanted Blue for the clothes.
Use a large flat tip brush to apply the paint (something like a 1/4" wide brush), and thin the paint down so it settles in the crevices. You don't want it so thin that it's like a wash, but you want it thin enough that some settles in the crevices and some of the white undercoat shows through. This will give the pale look and add depth.
Load up plenty of paint on the brush and slop it on, once it's on you can spend a minute cleaning it up, but speed is the key because the paint is drying and if you brush over an area that has partially dried paint it will give you ugly lines and smudges.
Do any exposed bone with Rakarth Flesh, exposed guts and blood with Mephiston Red (though you could probably use Blood For The Blood God, I painted these before that paint existed!)
Once that's dry, just slop on a heavy brown wash. I recommend Army Painter Strong Tone (the ink rather than the dip).
http://www.waylandgames.co.uk/army-painter/warpaints/warpaints-strong-tone-ink/prod_15994.html That's pretty much identical to Devlan Mud.
Because you apply the paint with a heavily loaded big brush, applying the coats only takes a few seconds per model. Do a batch of 10+ Zombies at a time so that you don't have to wait for paint to dry. You should be able to get a decent sized regiment done in a solid afternoon of painting.
The only tricky part is getting the consistency of the paint right. Too thin and the model will end up too white, too thick and it won't have the depth. When I started painting this technique, I'd have some scrap models (saurus shields to be precise!) undercoated white to test the consistency before actually slopping it on the models.