This is done by copying an unused hotbar to the desired hotbar.
An example of a macro that does this can be seen below:
/hotbar copy thm 5 share 9
This macro copies thaumaturge's hotbar 5 to a shared hotbar, 9.
This can be done between classes, jobs and shared hotbars.
Its best to use classes that you don't use, such as Disciples of War and Magic that you have already leveled, as jobs do not share the same hotbars and classes.
Personally I use this system to display:
- Commands
- Commonly used Emotes
- Crafters/Gatherers
- Jobs
- Minions
- Mounts
- Potions/Fireworks
- Signs & Waymarks
Hotbar 5 replaces shared hotbar 9 to show jobs
Hotbar 3 replaces shared hotbar 9 to show crafters/gatherers
If you need more than a class provides, you can always use more than one. I use thaumaturge and rogue.