All you do is hook up to the scanner and change the variant code, or if you don't have a scanner you will have to obtain a copy of the Diagnostic Manual and read up on the manual variant coding procedure.
Such is available for a fee at
www.startekinfo.com
But, I think you originally asked for outside temp and that would be displayed on the instrument cluster and if changable would have to be done with the scanner on its variant programming. Of course if you went to the diagnostic manual you could find how to display outside temp on the AC display through actual values.