Well, I've scanned hundreds of my own Kodachrome 25, 64 and 200 images on a Howtek drum scanner, which can actually "see" the color of the base of the film. My scanner is profiled with a Hutchcolor Velvia target and here's what I see:
When I scan Kodachrome, or any film, I always include all of the film including the rebate edges. When scanning Ektachromes, that rebate edge will come in somewhere around 6 Red, 5 Green and maybe 3 Blue. The scanner actually sees the color of what we perceive as infinite black but really isn't. When scanning Kodachrome of any variety, the RGB numbers for the film base come in more like 8 Red, 6 Green and 25 Blue. The scanner is seeing the bluish color of the film base and reporting back as such.
My solution, whether scientific or not, is to manually push the black point of blue channel down to where it would be when scanning E-6. Trident - the software that runs the Howtek - has a very easy way to click down those values independent of each other, and dropping that blue channel down in the shadow end also affects the entire image, but on a gradated basis. It's almost magical when you see the color come right to where it's supposed to be with each click.
As I said, I've scanned many hundreds of my own images and this has worked every time. As for people who complain about whether a particular method is scientifically accurate or not, it really doesn't matter. I have yet to see an image of mine or anybody else's that could not be improved upon either in the scanning software or in Photoshop later on. I'm going for the best possible image and can't wait the last sixteen rolls of Kodachrome I sent in after Christmas to arrive in the mail.
As for the drum scanner operators who claimed they couldn't scan Kodachrome, that does not surprise me. So many were just scanning bots who never really understood the why of what they were doing. They were the same people who thought drum scanners sucked for scanning color negs as well. I imagine most of those folks have been retrained for other jobs by now anyway.