Zig-zag to the top of the map, while being careful with the d-pad while you're between the lasers.
Now place a portal on the right wall by the top right cube, then push it to fill the gap to the left.
Move to the spot above of the bottom right cube. Put a portal on the south wall behind it, then one at the same place you used for the first cube. Now push it through the portal and all the way to the gap in front of the elevator. Done.