Why don't you use WIT (Wiimms ISO Tools)? It's the best tool for converting/editing Games, imo. Though, you need to be a bit familiar with the command-line input, but you should get the hang out of it quickly, it's not that hard to use.

 

Try Wiithon if you're not familiar with command-line inputs.
It's pretty easy to handle and IIRC you don't even have to compile it yourself, since it's available as debian package. So there's that.