My trackball doesn't have a mouse wheel, so the defailt zoom out/in is unvavailable. I can go into 3rd person mode, but I'm zoomed so far in I may as well be in first person.

There's no hotkey setting to allow you to set your own zoom in/out hotkey, and I haven't been able to find a zoom hotkey by random keypresses...

Hold F (default key) and move the mouse up or down.