K

Hmmm, first off you need to strip clean the areas being dyed. Something like Fiebings Dye Reducer will clean off a good proportion of finish/wax etc that it has accumilated over the years.

Then I'd recommend Fiebings Oil Dye - their basic dye in OK, but can leave a lot of excess on the surface, which will spread and mark the white parts when you buff it off. Oil dye is the better one, better penetration and coverage too.

You can apply it with a brush, but you'll get a better finish if you use a short-pile piece of scrap sheepskin. Though then it's not that accurate on the edges, so I'd recommend masking off the white areas thoroughly.

Give it a couple of coats then buff it up with another piece of sheepskin or a duster. Then if it needs it give it another coat - but you should get a good finish with just the two. Then give it a good going over with something like Acylic Resolene (apply sparingly and work in well to the dyed areas).

Then give it a couple of days to rest, take off the masking and give the whole thing a good work over with nikwax or some other type of waterproofer. Though be careful it doesn't cause any bleed across from the newly dyed parts - it shouldn't do, but it's best to work each section separately the first couple of time you proof it just to be on the safe side.