Scale Xpos

Hi i have 2 boxes in the scene 1 on the left 1 on the right there attached together then i am selecting the 4 vertex on each box that are facing each other and trying to scale them X-pos so they can meet each other in the center but its not working its going ether to the left or right not the middle this is the code i used so far Thanks

vSel = $.selectedVerts
in coordsys local for v in vSel do
v.pos *= [0,1,1]