What is the best method to use to try to remove old fingerprints from SA/SS blades without eliminating the crossgraining? I've read posts about using Semichrome, Peek and Flitz but don't know what is the best method.
Many thanks for any input.

You can try using semi-chrome, etc. But anytime you are using an abrasive polishing compound you are removing metal however small the amount might be all depends on how abrasive the polishing compound is. Semi-chrome has a very fine abrasive, that is why its often named as a good blade cleaner here. Nevertheless fingerprints will be very difficult to remove with out removing some of the crossgrain or at least the depth of its visibility on the blade. You can just work at it slow and with the grain and try to remove the majority of the print without destroying the crossgrain. Maybe find a happy medium between removing the print and lighting the graining of the original factory polish. That's what I do because it don't matter how great of crossgraining is left if there is and old fingerprint right in the middle of it.

You can also use a very fine sandpaper, around 2000 grit or more. It is more of a polishing paper than "sanding" paper. It does remove metal, as do all abrasive material. You can coat the affective area with a light oil or other light lubricant and work on the prints, using very light pressure and increasing it accordingly, if needed. You may have to lightly run over the whole blade to make it uniform in appearance once the prints are sufficiently removed. The "happy medium" Adam mentions is probably what you will have to shoot for to remove the prints.