lol, actually you could probably just tape a temp sensor onto the intake tube and have a readout in the engine bay, and yeah, i realize that co2 is really cold, but keep in mind that air isn't the greatest conductor of heat, and probably won't cool down that much, i wouldn't guess more then a few degrees below the temp of the air coming into the intake
also if you try this, insulate the system from the engine bay as much as possible, your system will be heated up a good amount if their just sitting exposed in the engine bay