Just illustrating the difficulty I'm having finding this information as a new user.
* Visit the X3 Live page: http://line6.com/legacy/podx3live and observe it's fairly non-functional. But in the header there's "Custom Tone".
* Visit the Line6 Custom Tone page, there's patches galor, but there's nothing clearly indicating what app to use: http://line6.com/customtone/browse/podx3/
* Click Help to hopefully get some help, there's no direct downloads for whatever app should be used, and it only textually references Line6 Edit.
Or try this.
* Visit the Downloads page and select POD X3 Live and Mac OS X: http://line6.com/software/index.html
* You have to scroll 2/3 of the way down the [very long] page to even find GearBox and it doesn't clearly mention what it's function is.
I'm not at home with my X3 Live to check, but I did install Monkey and I don't recall it including an option to install GearBox, Line6 Edit, or any other obvious software to help me out with this.
Thanks for your help, I'll try GearBox later this week and report back.