subtracting 273 is not hard at all.... if you do 'set temp blah 273' it will end up at 0C, and 273K, its not hard to figure out, if you realllly need help, get a calculator next to you.
@cracker64 Okey, but next time i modify the source to get it easier. Of course I'm not Developer yet, but i have my mod and have temperature in your console modify to Celcius.