Not officially supported by Nintendo. So you are not "supposed" to use a HDD on the Wii / vWii XD (yeah, i know, i know )That's were you are wrong dear @Omegadrien ,you could use a HDD for storing the games you wish when using the Homebrew Channel (see the URL given by @walterdavid earlier there is a fully written tutorial about that).
I, however, wish to 'share' that same drive between the two systems.