I've done some headrest in the past using SEM Landau black spray dye, you can either get it in spray can or qt for gun spraying, I would suggest right after you apply the Landau black, that you use SEM's clear dye over it, low lustre clear or semi gloss clear, your choice, I generally prefer the low lustre clear as it looks more natural/factory sheen, the semi gloss will look like it's been Armour All'd...either way be sure to spray a coat of clear to preserve the color from wear, avoid heavy coats of either SEM product, 3 light coats of each is more than sufficient
Mike