Not through modifying HBC. Through writing your own software which enables the faster CPU (I saw no mention of RAM in my skim read). It's not a case of "modify HBC and all apps will magically use the extra stuff". It's a case of having some code at the start of your app which enables the extra cores, and then your app can use them. But not with libogc (at least, not properly), which is the standard homebrew development library for Wii (and therefore, vWii).Rather than make a proper program platform for Wii-U homebrew, marcan has posted the information to activate the wii-u's ram and such in vwii mode threw altering the HBC.
However it is all in tech talk. He hasn't provided any programs. I'm not a programmer. If someone or group made the necessary changes to the HBC, I'd reconsider buying a Wii-u. I'm all for better homebrew.