Well, I failed in setting up Riivolution too. But happily, I stumbled upon a Brawl texture pack for it. I took out the xml and everything started working.
So, here's what you should do (instructions written quickly, it's been a while since I've been setting up Riivolution).
1. Install Riivolution (this one should be easy enough).
2. Download this:
http://www.mediafire.com/?662ybji53sjyhvv Sadly, I don't know who made the xml files, so I can't give credit.
3. Unpack the files and put them into the "riivolution" folder in the root of your SD card.
4. Put your hacks into the "ssbb" folder in the root of your SD card. They have to be unpacked, btw.
5. If you want to use codes, put the gct file into the "codes" folder in the root of your SD card.
6. Run Riivolution.
Should work.