No, this is not possible. SVideo is only 480i (576i in PAL nations). The Wii will not let you select 480p output unless the mode pins are jumpered in the back -- one of the features of the component cable. Composite and SVideo cables carry standard NTSC (or PAL, Secam, whatever) video and cannot do the high resolution.
To correct some of your incorrect assumptions on SVideo I suggest you visit: S-Video - Wikipedia, the free encyclopedia