you can extract wads using showmiiwads, however it will not help you in this case. if you want to play downloaded wads install them with wad manager 1.7 and then you can move them to the sd card. if you want to play downloaded wiiware/vc from your sd card you'll need to patch your system menu ios(ios60 for sm4.0 ios70 for 4.2 or ios80 for 4.3) there is a homebrew app called triiforce that can run wiiware games without installing the wads but you'll need an extracted nand dump and compatibility isn't perfect. i'm not even sure triiforce is even updated anymore. so yeah you'll basically have to install the wads.