In a bowl mix the jello with boiling water and stir to dissolve 2 minutes then mix in sierra mist. Put in refrigerator for 2 hours to chill.
When jello is chilled remove to counter top and with a fork stir the jello well to break it all up finely. Then add cool & whip blend well then fill the pie shells you have placed on a tray or platter with the jello/cool whip mixture. Set back in refrigerator for 1 hour or until ready to serve.