For those having trouble, there's a way to move the active l-click/r-click across the bar to different positions, it's in your settings - Game Tab. In View and Edit Controls, it's Switch L-Click Ability Slot to Next/Previous. Bear with me. Set one of these to some random key that you'll never use. Backslash works for me.
Now, move your mouse clicking over to position 7 or so. Leave your primaries in that position.
This leaves you 1,2,3 for direct access, gaining you those keys. 7/8 are your L/R clicks. 4,5,6 for some optional utility spells.
I've found this seems to be the best choice for access to a variety of things all at once, at least for me. Hopefully that helps a little.
You can also edit the mouse buttons themselves to point at 7/8 directly if you go further in the list (on page 4/5) you can set "Use Mouse Ability" to be something different. If you want to get really fancy you can hook up light ball to your left mouse as a utility and drop a few hundred of these as you fly through the landscape. I don't recommend it as a permanent setup but for giggles it was quite amusing.
"It's Dark! I'm blind! Shoot someone!"