Yo Cancerblack. I imagine you have some experience with paints from the modeling and stuff?
I have a 1/7 scale figure that will be here eventually (shipping was pushed to November though) and one of it's features is that for "demon mode" you can insert a light that's sold separately inside the horn for a light up effect.
The only issue I see that the light recommended doesn't really come in a pink.
What I have heard though is that you can paint the tip red to get a better effect, I don't know if that'd be on the red or white light since it's not mentioned which one (my own guess is red maybe). I'm hoping that you might have some input.
Here's the figure and light effect for reference.