Since someone doesn't like the way I replied, let me answer in a more thought out post.
This has been answered many times, and it is just not possible. Since the HD Textures alone are 200-300 megabytes, and N64 ROMs in WAD form can't go above 50megabytes, inserting them would be impossible.
As for emulation, there isn't a half decent N64 Emu for the Wii yet. Even if there was, the HD textures are just too much for the Wii to handle. It's not a matter of processor speed, or graphics chips, it's just too much data. It would be like trying to run Windows Vista on a computer that was designed for Windows 95.
Mhm...yep, HD is definitely just too much size, forget this...but: from
EmulateMii:
QUOTEWe have a vision of supporting custom texture packs in Wii64, so we will implement that feature as well.