I have found it is helpful to use a plastic prep solvent, and to also scruff up areas of contact with 180.. Gives the glues and epoxies something to grab.

Kenneth O'Gorman
Fix N Stitch

@Andy Fabianski

Chrome tanned leather has a finish on it from what I understand. It will be similar to that of automotive leather like @Ceasar mentions here. You will need to break this finish.(make tacky) First clean off dirt with a water based leather cleaner such as z-7. The next step will be to remove any oils that might be present using a alcohol based cleaner preferably silicone wash(rinse step).. Apply wet application and let dry. Next leather prep, yes a heavy solvent.. No you will not damage the leather you are only trying to penetrate the color finish that is already there making it tacky to the touch. If there is no color finish present no need to use a leather prep. Next you will want to use a water based dye. Choose wisely , or mix the color yourself from primaries. I have found that a mixture of black and dark brown and violet will help to create darker colors. Rub your dye in using a paper towel. Let dry and continue this method until you achieve the finished look you are looking for. You will need to add cross-linker product to water base dye to prevent UV damage and improve adhesion. I would also add primer designed for leather adhesion in my first coat of dye mix. There are many available. After you achieve the color you like, you will need to add a protective water based top coating.

Hope this is useful, if you have questions or if i have misunderstood Id be happy to help you complete this project as I have dyed all sorts of leathers.

Kenneth O'Gorman
Fix N Stitch