I'm sure someone will correct me if I'm wrong but I believe all you need is HBC to do what you are wanting to do. One thing I need to correct you on is NES, SNES and N64 (as you called them) are not wads, they are simply apps or in this case emulators. A wad is something that gets installed on your wii and apps just run using HBC. If you go here you can find the emulators that you are wanting. They need to be placed in your apps folder on your SD card.
you will also need this
SD:\fceugx\roms (put your games here)
You will find something similar for all the emulators. Most have a readme file that explains this but if not just google it or search this site and I'm sure you will find something.