That was the one reason I had to buy an F80 instead - no manual ISO setting capability. I find that extremely annoying and they're probably a great machine otherwise. Well, except for the dopy metering selection system.
You certainly used to be able to buy cassettes for bulk loading film that had dx codes of 100 or 400. I think there were also dx ISO labels available. Might be worth looking into if you'll be using a lot of bulk loaded film with this camera.
I have run into the same problem using some Superpan film in my N5005 which only uses DX coding also. The Rollei Superpan 35mm cartridge has no DX coding and I want to use it at its true speed of 160 ASA
The next step is to scrap the paint off of my cartridges where needed and (in case the paint on the cartridge is an adequate electrical insulator) I will put little squares of Scotch tape where it needs to be insulated.
I haven't tried the above yet but will shortly and report my results.