Old Engineer
Harry it is deadset so simple a trained ape could do it...Heck even I can do it.
I used the RIT liquid dye as opposed to the powder...Cherry Red...
Boil the kettle
Pour enough boiling water to cover the knife into a stainless steel saucepan .
A slosh of vinegar.
A large slurp of the liquid dye
Immerse knife spine down so both scales get even coverage.
Stir it round a bit.
Another slosh of dye and a dribble more.
(measurements are not precise)
Steep for say 30 min max ...maybe less.
I kept taking it out to check.
When it looks right remove and rinse thoroughly under cold tap.
Be careful not to splash any dye on kitchen surfaces or clothing (or penalties will apply).
Dry with paper towel.
Something to be wary of is that the dye solution is alkanlinic and very salty...it will affect metal surfaces eg shiny blades and backsprings...the bolsters not so much. It left black marks on the blades (see pic below) but that comes of with metal polish...Im sure that they could be buffed back to mirror finish if so desired.
Cheers.