i'm after a couple of those plastic S switch holders as well, to replace a cracked one and for some custom S7 bodies i'll be routing this summer. the info i got off the japanese Ibanez page calls that part SWITCH COVER PLATE 4PT1S5B . i don't think Rich has these in stock at Ibanez Rules, but you should give him a try. Ibanez dealers should be able to order them as well.
you could certainly carve a piece of wood to look like that plastic thing from the top, but the bottom has threaded posts for two nuts inside the control cavity. i'm not sure there'd be enough thickness to somehow attach bolts to a sliver of wood like that.
the roundover on your S body looks sweet. you probably did that by hand, right, since a router bit wouldn't evenly follow the arching top? i plan to make my custom S7 bodies thicker than stock to increase the overall amount of wood, but i think i'll try that roundover on the edges as well.