For 2 tone I would brush the lighter color on all of it and then using something like this hit the high spots with the black . Be sure to dab the black off onto paper towel before going to the hide , you can control the amount better.
This is just a small piece of hardwood wrapped inside .
If you want the ( secondary knobs ) lighter like I understood you to begin with , I would use a very small brush and resist them before applying anything , them same as above . This is how I would go about it but I haven't ever done one