This will allow you to run SSX Blur from a USB Loader.
1. Open a backup copy of your SSX Blur ISO in WII Scrubber (I used v1.30)
2. In partition 2 right click on ssx.dol and extract it to your desktop
3. Rename ssx.dol to main.dol
4. In patition 2 right click on main.dol and replace it with the one from your desktop.
You're done Simply install the modified ISO on your WBFS drive, load and play. :)
There's a similar fix for Mortal Kombat here: