Hi Greenshedman,
Follow this link for how to and lots of info.
https://www.furnitureclinic.co.uk/Ho...re-Leather.php
I believe their products are available from amazon and try looking up more videos on youtube.
I looked into this before to restore sofa colour but I think changing from white to black might involve many many coats of dye and a lot of preparation. There is also a company is Ashbourne who do this.
http://www.ashbourneleathercare.
Good luck with it,
Lucylugs
Lol, just saw the date on your post! Nevermind maybe someone else will be looking for the info.:)