In general you only change Up once. For VRML it should be defined as the Y axis. Back to the cube. It should still be in edit mode. You can constrain the rotation axis by selecting either of the default constraints under Major or Minor Axis in the Edit window.
Large arcs appear to indicate the constraint axis.
In fact it works the same way, but now instead of the object moving when you drag in the red point, it is scaled. The defaults are different to. The planes are now parallel to the various axes of the object. Play with it to figure out which is which. The same rules for constraint combination apply.