For the water cooling I milled out grooves in the base plate right under the IGBTs. The plate is 3/4 inch thick so there was enough depth for it. This really isn't my idea, I borrowed it from forum member 64jeep. It was in his electric porsche blog.
In the side of the plate I drilled 2 holes and then tapped them to run the water lines.
Most likely I will be using a motorcycle radiator to cool the fluid and a swifttech pump for circulation.