Chris.
I made cooler box (
a Gary Honis knock-off) capable of running my DSLR at or below zero. I noticed that when ~8C the sensor thermal noise was pretty low so anything below 8C is a good result.
I managed all this by using old computer HSFs,
milling some material off the inner HSF so its base protruded out of the side of the box. This directed the cold to the inner of the box. The result was quite successful.
But....you loose a lot of thermal efficiency attaching the nose piece to the focuser so this needs good insulating as well, which elongates cool down times.
I used a cheap ebay temp controller. Yes it's not PWM thermal control, just on/off thermostat but... meh it works. Just note some of these controllers are 240V but you can get 12V versions.
DSLR mods yahoo group is another good resource.
edit:
Oh IMHO...run your cooling Peltier system from a separate 12V source than the rest of the scope stuff.