Kodachrome works differently to E6 - something about the dyes being added during development ? But I have no idea about just doing the First-Development stage, or even if there is a simple first-dev.
If you are very curious, or the roll may contain something old-and-interesting, then I would suggest sending it to
Dwaynes, as they are the only place processing Kodachrome anymore. From their site it seems to cost only a few dollars.
Is the cassette marked K-14 ? I think I recall reading that there have been a couple of variations on the Kodachrome process, so if it is really ancient then it might be a problem. In any case of doubt I suppose contacting the lab would be a good idea.
Needless to say, many of us will be interested to read what comes out of the film.
EDIT: A bit of googling found me
this, from someone at Kodak about four years ago. Basically, you probably cannot just process a first-dev stage and end up with any sort of useable image.