Old topic, but maybe there are people around having a similar problem (I don't have Windows, so had to figure it out).
Start "winefile", this is a file manager similar to the old Windows one, running within Wine. Browse to Drakan, and double click it's exe holding SHIFT down. That way Drakan will take it, and you can select developer mode on the setup screen.
The configuration is not in the drakan config file or anywhere else within the game directory, but in the registry. I confirmed by having an other copy of Drakan, which reacted the same way (having developer mode enabled) once I enabled it in one. The keys are on the [HKLM]/Software/Surreal/Riot Engine path, but it is a binary mess which I didn't want to manually compare now, it's enough that it works.