Use an old CD-ROM mechanism... i have one that moves the tray 6,4"
i'm pretty sure that the rails will be hidden for the most part. the only area that will be showing would possibly be the sides.
cool... but you're a couple months late...
2006 Mazda 3Behringer DCX-2496JL300/4 Focal 6W4311B Focal TN52JL500/1 JL10w6v2
just for the curious and the engineers, check out www.sdp-si.com. Don't get your motors there... they're wicked expensive, but for racks and small plastic gears and all kinds of otherwise wicked cool little bits, it's a great resource!