I have attached a quick unfinished sketch made in Photoshop that will be developed for digital and screen printing on fabric and paper. It's basically a mix of hatching and erasing in different opacities using the brush tool in white and the eraser tool.
Illustration http://f.cl.ly/items/2u181m1T30040u2z1l1s/Jacket.png
Now given that I'd like to be able to easily change the color of the illustration (to different spot colors) while retaining the shading I thought it'd be best if I tried to recreate it as a vector drawing. Is there an easy way to recreate this or does anyone know of any techniques I could use to achieve this effect in Illustrator?