OK. Mac or PC?
Pretty sure I get what you’re asking for. I can only speak for the mac side though. So, the first thing you want to do is Gang Source and Program Monitor. You can set this through the flyout menu on either the Source or Program monitor.
Move your cursor over a Monitor window (no clicking required) and use a two-finger scroll to the right or left on the trackpad (laptop or magic trackpad desktop version) to move through the footage or along the timeline. With the Apple mouse you get the same effect with a single-finger scroll across the top of the mouse.