The scheme is in
IA: Masterclass Vol.1
IIRC it's
Codex Grey helmets and coats (airbrushed on)
Graveyard Earth Fatigues
Burnt Umber (scorched brown) for boots and equipment.
They don't list the other colours however, but they do tell you how to mass paint them quickly.
EDIT://
not sure if this'll help, but I tried to base my engineers on the
FW website ones.
There's more pics of them in my gallery if you want to see them.