Unless you have a very large tub and lots of dye (and probably even if you do), I would think it would be difficult to get a made up garment evenly dyed.

I dyed a couple yards of white cotton canvas bright orange in a turkey fryer 13" (33 cm) diameter, 16" (41 cm) high. Still came out blotchy, but it was for my sons' Halloween costumes so no big deal.

Don't think I would try it on a fine wool jacket.