I ran into the same problem when I built my Idolo. After trying transparent ink over a silver base and fluorescent blue over white (both looked really tacky IMO), I settled for a simple mix of Tamiya sky blue, a drop of yellow, and white. I had to thin it so that it would just flow into the narrower lines, and so I had to apply two coats. If I ran over a border, I could just wipe away the paint with my fingertip.
Masking these lines is just asking for insanity.
My Idolo album