Hi – this is probably both more and less information than you wanted, but
1. Schill led an ad-hoc freikorps behind French lines in the winter 1806-07 war, and the men came from a variety of units and had a wild collection of uniforms.
2. After that, he became Chef of the 2nd Brandenburg, and they had the regulation uniforms, BUT
then he led his uprising and recruited men from a variety of places.
3. For the next two centuries Germans produced idealized images of him and his rebels, despite not knowing the story very well, and thus you have any number of erroneous prints, full of confusion and inaccuracies regarding Schill's uniform, his men's uniforms, and even which Schill freikorps they're talking about.
When I wrote my book about Schill, I came across no fewer than 400 biographies, most of them amateur, full of an incredible variety of illustrations, many times in color. During his life and thereafter, Schill was the subject of a zillion pamphlets and broadsheets and home-collectibles like souvenir dinner plates, teacups, key-chain fobs, necklace cameos, children's coloring books
you name it. I've seen Schill in every imaginable color and pose.
So: if you specifically want to do his hussar regiment in 1808/09, then it's in the regulation cut and color. But if you're doing his revolt
then pretty much anything goes. He even recruited from deserting Westphalian, Saxon, and Mecklenburger troops, former Swedish militiamen in Pomerania, Prussians from various units, and of course civilians.