The question is which sawmill.
The Thermal Expansion Windmill is pretty easy to use. Just supply it with Buildcraft-Energy (the machines that produce them normally have "Engine" in their name and all look pretty similar.
If you mean the GregsTech-Sawmill (which is not in the Modpack yet) You need a ring of 3x3 area of machine-casings, 8 standard on the outside and a reinforced casing inside with the sawmill block on top. The advantage of the Gregs-Sawmill is that the wood-pulp can be processed to something similar than wooden planks... but well you should not have a lack of those anyway and the machine is difficulty to power compared to the very easy TE machines.
