There have been threads on Rangefinderforum about processing color negative and slide films as b/w. I have never tried it myself, but some seem to think it works out nicely.
BobF - Kodachrome did use an exposure to light in its reversal process. I seem to recall that the original Kodachrome did, but that is was a process that could be done at home or in a drug store. Probably different chemicals, or under different laws on the environment. Perhaps Professor Lynn can clarify on that.