Based on limited testing, and with the help of X-Rite I can report that calibrating and profiling a 35mm scanner with a Kodachrome K3 IT-8 target to scan Kodachrome provides a significant advantage and much better fidelity in reproduction of the image attributes as seen in a Kodachrome slide.
But for most this will probably remain a problem to achieve as Kodahrome K3 IT-8 reference target slides are not readily available, and not all calibration and profiling software (notably Lasersoft SilverFast will not) will read and calibrate from the old "Marilyn" format Kodak IT-8. Possibly Microtek ArtixScan model scanners with Kodak color management profiling utilities will. Otherwise I had to borrow the use of X-Rite i1 Photo which is a very expensive professional hardware and software package, to be able to calibrate and profile with the Kodachrome K3 IT-8 target slide I purchased from B&H.
But although my testing is in an early stage with just one of three scanners I have, the results are very positive. So for those who want ultimate scan quality and have libraries of Kodachrome slides to scan, finding a way to calibrate and profile a scanner specifically for Kodachrome wil be a worthwhile goal. I will explore what resources may be available to accomplish this as I have time. For now, more testing to learn as much as I can how to use this newly found capability.