Anyone have a good process for Kodachrome as black and white neg?

We have three rolls of Kodachrome 64 that a customer wants processed, and is happy with a black and white neg.

(Unfortunately I couldn't persuade them to go for Stephen's $260 colour process offer, but I tried)

Does anyone have a good process for this? I have heard that a C41 bleach is useful, but I'm hazy on the exact process.

Any help gratefully received.

Matt

Did you see the sticky?
(there was a url link here which no longer exists)