I thought of a simple way to play quarter tones on the guitar and actually aplied it in mine with fruitfull results.

What I did was tune two adjacent strings a quarter tone apart. In this case it was the E and B strings. So now if I want to play a 24 quartertones scale going up I play B open - E open - B1 - E1 - B2 - E2 and so on.

Messing around with it produced some painfully out of tune mess but the good thing is it opened a new door to available tone colors.