Not a hard fix, but it is very easy to make it a much, much bigger issue if you're not careful, especially with power tools. Seems there's been some threads over the past year on this.
How much scratching? If a few, you may want to just do sandpaper them by hand (buy a kit at a fish store, Neptune's has them) then finish with novus (3, 2, 1). If more than that, probably easiest to sand down the whole panel with a rotary tool then novus finish. Tom at Aquamart can sell you a pack of rotary pads for this (if you don't have access to auto shop tools and supplies).
I would follow this link (procedure and level of sandpaper to start). Also you can only jump 200-300 grit between steps (for example, if you need to start at 800, then you need to sand - 800, 1000, 1200, 1500, 1800, 2000). Do wet sanding, if possible.
http://www.sisweb.com/micromesh/reference/aquarium-restoral.htm
I wouldn't do inside the tank unless you really need to. Mixed results, some people say you really need to drain the tank below the scratch then sand out carefully so acrylic shavings don't get in the tank.