The Tuner in the 3803 does support Discrete codes. The Tuner has 5 Banks, and 8 Stations per bank.
The Atkis remote that comes with the 4802/5802 has all discrete codes available and there are several CCF's of it here in the files section. Try
This One its a button for buton remap of that remote and has all the discrete Tuner codes within.