Until recently I was under the impression that Freedoom does not have its own cheat codes because they could only be implemented with a custom executable. However, not log ago andrewj told me that cheat codes can be changed using the BEX format. (I haven't found any reference on how to do this so far though.)
If it is ever decided to change cheat codes to be different from Doom (to which I suppose there should be no reasonable objection), I was thinking that maybe the new codes could serve to give credit to Freedoom contributors? A precedent for that can be found in the demo version of Hexen, where the cheat codes are names of Raven Software developers.