No cutting of texture needed. One way to do it is in the TCE. Select the sides and remap to front/back and left/right. Make sure the "keep size ratio" is on. also move the surfaces out from the texture so you have four individual sides visible. As you se in my picture I have re-sized the square to the same height as the rectangles. make sure you re-size proportional. Then select one side and in the "snap" part of the TCE click left and bottom. This is one way of doing it. Hope this helps