Z-Man,
Get one of these:
http://www.broan.com/display/router.asp?ProductID=543 and install it in your attic, bring the exhaust outlet through the roof (like Curt said) and run a vent from each room (bath and bedroom) to the unit. Cut the drywall, screw the vents in, cover with diverters, mount the motor/fan assembly in the attic , wire it up to a switch and exhaust it out of the house...you're all set.