How to accept align on Overlay?

[wthreex]

I'm trying to add logo with overlay method but it seems there is no argument for align property, so how to do that ?

[StainlessS]

x,y default of 0,0 = top left
0,c.height-logo.height = bot left
c.width-logo.width,0 = top right
c.width-logo.width,c.height-logo.height=bot right

EDIT: (c.width-logo.width)/2 , (c.height-logo.height)/2 = centered ... etc