You can water the paint down to basically "dye" the pants. You don't want to straight paint it as they will be hard and not pant like. It's kinda trial an error thing while you are doing it and how it feels.
I'd suggest after painting them to kinda crumple and massage them to loosen the stiffness, also I would do it after they are dry too. This would be before you paint the darker knee area and add the knee pad.
I'd suggest after painting them to kinda crumple and massage them to loosen the stiffness, also I would do it after they are dry too. This would be before you paint the darker knee area and add the knee pad.