Unfortunately, the classic denim jacket probably won't work. Most jackets have contrast stitching and a very distinct "worn" look to them, where the dye settles into seams and wears off of certain places, making the coloration inconsistent. Most denim jackets are also made using a fabric with different thread colors woven into the fabric - some threads are blue, some are white - and it gives the fabric a very distinct look that will stick out as being earthly.
If you have a jacket that doesn't look like the usual denim jean jacket, though, it might work, but probably only if it's a solid color besides the classic indigo blue. Many coveralls are made out of denim (mine included!) but since it's a solid black, gray, or green, it doesn't look like a pair of jeans. If you really want, you may also be able to use Rit dye and color remover on it, to change the color or at least give it a solid-colored look.
Do you have any photos of the jacket? Seeing it will help!