I don't really see why using an hdd would be an issue, since the wii has 2 usb ports, so you have one for the hdd (even if it needs a Y-cable to get power you can use an extension or just plug it to something else) or just a pendrive, and one for the controller . Also, you could use the .ini that goku junior linked to "as is", since the first part is ignored by nintendont anyways (it's just a short description that allows to list some controllers that work with it)
Also, it works only for the controllers that have said PID and VID, if yours is different it could work after some editing but depending on the controller other inis might be better. Anyways, I would suggest you don't try using the cache.txt until after you've got the games working, otherwise it will be harder for you to find out what's keeping your games from loading.