Advice on repainting keys on phone?

[Guest Alex_le_brit]

I've managed to scratch the paint off the two keys with the green pick up and red end call symbols on. The symbols are stilll there but the paint's been rubbed off next to them.

Does anyone have any advice on the type of paint I can use to successfully retouch these scratches? I'll obviously need a very steady hand to repaint the scratches without painting over the "window" which lets the light through to show the symbols, but I'm used to fine detail work.

I know there's been posts about repainting the casing, but I've not found anything on repainting the keys.