Now you have two options: you can either play your mods on Dolphin(Though it's difficult to add Gecko and stuff to Dolphin; not recommended), or you can use an image burner(Like ImageBurn) and a blank cd to make the new .iso you made into a cd. You can then insert this cd into Brawl, and then not have to put a custom common5.pac on your SD card, because the common5 will always be there now(Unless you do put a replacement on your card) and it will be a PAL version, so as to not glitch or anything. Now you can just load your hacks as normal, and the common5 will be whatever you wanted.
Quoted from my comment above. My main point in my quote here is in blue. That is the only thing I changed in the quote, is the color; everything else is identical. So yes, this was written for Wii users.(Though it does work for Dolphin)