What other inputs does it have? HDMI? Or maybe VGA/DVI? Or maybe even BNC?
Maybe the component -> HDMI route could be a good idea. If I'm wrong, someone please correct me but, if you use component cables with your Wii, I'm afraid the output resolution will be too high for RGB scart. Maybe a "cheap" investment would be to see if you can find a DVD recorder or similar with component in and HDMI out? There are also no-name converters on eBay.
Edit:
Reading
here I see you should have component input, just with BNC connectors instead of RCA. So just look for adapters with a male BNC end and a female RCA end. The BNC inputs on your display should be labeled with what color goes where.