I've used silk ties in a quilt, just in small corner pieces and I stabilised it with an iron on interfacing before cutting.
But for something much thiner, you need to get a piece of cotton that will highlight the colours (like white) and use fusible bond to fuse the scarf to the cotton. It would pay to use an applique mat over the scarf to make sure it doesn't burn / melt / disintegrate when you iron it! ;-)
When we did it we actually used two layers of the thin material, it made for an awesome effect.