In the visual editor, point the cursor at the left of the button and then click the "Center" align button.
A
acpan author9/22/2011
Thanks Christain, Placing the cursor does not work but you did point me to the right place.
And by selecting the whole button and click the center justify, it worked. But anyway, i did not want to touch the visual editor, so the best way for me i found out was: Edit the brick file loginbuttons.htm and add <P align=center> in front. Regards