First off, make sure you have the Homebrew Channel installed on your Wii with either Gecko OS or Riivolution. Then, create a ''private'' file on the root of your SD card. Then, create ''wii'', then ''app'', then ''RSBE'', then ''pf'', then ''Fighter'' and finally, folders for each Brawl Characters.
This should look like this : private(wii(app(RSBE(pf(Fighter(*name of character*.
To add hacks, go to the Vault, download some and put them in the corresponding folder. If you don't wanna use them, just load Brawl normally and the hacks won't appear. Characters that transform need both the PAC and PCS file, otherwise only the PCS is needed for most characters. Here are some of the hacks I've created or collaborated, feel free to download them, some were collaborated with other people.
http://www.mediafire.com/myfiles.php#o0u39m6cavza7Enjoy!