One of bushings on my rear window is bad and needs to get replaced. I can't roll down the window using the switch. All I hear is a click at the motor and no action. I'm not sure if the motor is siezed or if the missing bushing is causing it to jam. So, is there a way I can roll the window down without power?

Yep, unbolt the window regulator, slide the runners out of their tracks and the window can be manipulated by hand. Your car should have bolts/nuts holding the regulator to the door frame. Later cars use rivets that have to be knocked out (and replaced with regular hardware).