rreynolds,

Quote - It's often simpler to use the Direct Manipulation Tool (which should have a dials option to constrain motion to one axis).

With a prop you you can use paramiter dials to move the origin if you select "Display Origin" from the props 'Properties'. You don't get to see the 'endPoint' this way, but then you don't usually need to change this unless you are going to use "Point At" on the prop. Generally you should change the origin when the prop in in it's zeroed state. Otherwise changing the origin can move the prop.