How do I move the pivot point of a given object manually, using the blue/green/red arrows? So I want to not just center the pivot to the Mesh (which was possible using this menu)  but also to the bottom of the object, where it touches the grid. How do I do this manually or by entering values by hand into a box?
The best way I can see is so:


Create an empty and move it to the position of where you want the object origin
Press Shift S --> Cursor to selected
Select your object and go to: Object --> Transform --> Origin to 3D cursor


Ta Da,
Magic :-)

Hope I helped and best of luck,

BFB