Thanks Graham. By cooling the DSLR you're going to get a similar sort of boost to SNR (when compared with an uncooled equivalent). However unless you have a very old CentralDS camera (like a 350D) the ISO you should use may be different as your camera will have different gain settings as its 14bit instead of the 12bits that im using.
But yes, i would imagine the same principle would still apply: Determine what ISO maximises your SNR, and then vary the sub length and use HDR combine to increase the effective dynamic range of your image
ps as a side point, i'm curious to know what sort of condensation problems are seen with a cooled DSLR, when the cooling takes the camera below the ambient dew point..?