It is hard to see in this image, but I have a single layer of clear packing tape that covers the memory slots and extends to the base of the CPU socket. This is an important step, without the tape the clay will get pushed into the memory slots and disable them.
Continue laying down a layer of tape to protect components and then put down a layer of clay over them. In this picture you can see the tape against the PWM chokes and the Northbridge heatsink. You want to build up a layer of clay that is about level with the processor.
Once the clay has been applied, place a drop of TIM on the CPU and then mount up your liquid nitrogen or dry ice pot.
Here you can see how the armaflex sleeve around my F1EE liquid nitrogen pot mates up and imbeds itself in the clay. This insures a perfect air-tight seal.