there are two ways to go about this
1 leather dye and leather feed
or good old shoe polish and leather feed
but if going for second option make sure that the polish is put on in a vert small ammount and allow at least two days to sink in then gently polish the area and aply the leather feed again leave at least one day for this to sink in
if you dont then you will find the polish where you dont want it
oh I have thought of another two ways so here you are
get leather cleaner/feed/polish usually a cream spray on
so by cleaning and polishing the other areas of the item you should pick up enough on your cloth to cover the effected areas
rubbing this on the bad areas at regular intervals whilst doing the rest will transfer residue to the desired areas
once you have the colours as near as poss allow to dry and then polish but atleast once a month feed that jacket or it will crack and get to be a right mess
the other way is to take the jacket to super stitch and ask thier advice, or a leather specialist shop to find out what they suggest
my advice comes from years in leather sales and marketing
Andrew Jones, July 2008