I don't know if it's possible, it's just an idea, but how would it be to receive The cables from the BDU with an ENIGMA-encrytion so you can decryt it with an ENIGMA-emulator like this one:
http://users.telenet.be/d.rijmenants/en/enigmasim.htm
Also you can implement a Codebook in the kinde of rec-book with the correct key for the enigma for ervery week or month of the mission.
I know it would be a lot of math-work but i think it's quite a cool thought.
Greetings Empier
Edit:
Here is a link for the codebook maker:
http://users.telenet.be/d.rijmenants/en/codebook.htm
Maybe you can run the Enigma emulator on an Notebook next to you. That would be real Kaleun-feeling.^^