I use the tru-trac guides, they are good slides. I make a wood bracket out of 1/2" plywood that goes between the faceframe and the nailer strip on the back of the cabinet. Then I mount the cabinet member to the bracket extending 11/16" past the bracket so that it recess's back 1/16" from the face. Then the drawer member I mound 5/16" up from the bottom of the drawer. I then mount the brackets in the cabinet to faceframe only. The back is left loose until the drawer is inserted. Then I adjust the drawer to where the front fits nice and then nail the back side of the brackets to the cabinet. Since yours are retro fit you might have to shem between the bracket and the divider.
If your dividers are flush with the drawer opening I would cut some sticks to fit between the floor of the cabinet and the drawer opening so you can screw them in level with the cabinet floor of the cabinet. Put a minimum amount of screws into them until you test the fit of the drawer.