Quick Question: How to move only the centre of object without the object itself?

I need to move the center of my object so that i can apply mirror at the right spot. How do i move it without haveing to move the rest of hte object or vertices. Is there a way i can just grab the centre and move it?

Place the cursor where you like to have the centre.
Then hit the center cursor button in the EditButtons MeshPanel

great, thx