Regular wood stain works as well. Remove the enamel (rind to bowyers) first. A lite sanding will do. Just make sure the stain works with your finally finish.
There used to be a "toner" available to bamboo fly rod makers as well. I "flame" the bamboo first with a torch. Of course it is easy for me,I do the whole clum before splitting it. I have used MinWax stain to touch up areas that got to lite when planing the tapers.