Are you talking about Wii? Or Wii U? You posted in the Wii U section.
Either way, we have guides for you. For Wii, see the Softmod Any Wii guide. For Wii U, see the vWii modding guide.
Either way, see the FAT32 guide for formatting and installing content to the hard drive.
I don't know if it's possible, but it would be way too slow to be of any use to load games off of network. You would want your system to be attached to the file storage device.
Links to all guides mentioned are in my signature.