I am not sure if my searching isn't good enough but has anyone changed the pink color into something darker? Or even perhaps changing its texture like arrow or smaller line size? thanks

As far as I know, the progressive taxi lines are hard coded into the simulator and my guess is reverse engineering is probably illegal.

 

I may be wrong though in which case if anyone has done this with no legal repercussions, I'd love to change them too. I find the FSX progressive taxi lines look better than what we have in FS9.

Well, then my simulator illegally rewrote itself to make the pink line invisible. I no longer have prog taxi. :-(