The latest issue of Macromedia Edge newsletter featured a great Fireworks tutorial. Its about colouring background imagery by Alan Musselman.
I’d have to say that those images in which foreground subject is in full colour & the background is Black N White, look real good & I wondered that it must be somewhat difficult creating that. But this tutorial changed my opinion.
I’d say that you give it a once over & you’ll like it. 
You can read either Flash Version or Print Version of the tutorial. And there’s an example image on the first screen in the Flash Version. 
That is cool! Thanks for posting this for me.