In a small container, I mixed approximately 3 parts blue to 1 part black. To that I added a small amount of metallic pewter - I'd say it was about 5% of the entire volume of the blue and black. I tested on a low visibility spot in the back seat. Painting it on directly yielded a result that was too dense and looked, well... painted. This is a 15 year old car - its never going to look brand new but I was eager to color the spots where the dye had completely rubbed off. So I took a damp rag to apply the dye which allowed it to blend more effectively. I did two coats where the dye was badly worn off. Then I let it sit for a day (not sure what the bottle says about the dry time but figured this couldn't hurt.) Then finished the job with an application of leather conditioner.
My main worry was that it would rub off on my clothes or skin, especially with the heat and sweat of central Texas extending well into October but so far not a trace of that. Before and after photos attached as well as one of the paints I used. Hope this is useful - I couldn't find this information anywhere else.
