Player 2: There's a pillar near the end of the walkway where player 1 currently is, so set your first portal on it before moving to the right a bit and laying another portal on the wall across the gap. This will allow player 1 to pass through.
Player 2: Follow your teammate until you see the orange arrow, but stay here! If you look to your right, you should notice a couple of switches on a wall in the distance. This is your target.
Player 1: Once player 2 is in position, drop the crate down the middle of the slope and immediately run back through the portals and make a mad dash across the raising platforms and each of you should go for a switch. Now before the platforms give way, hit the switches together to release the first set of gels that lead to the exit.
Once you both hit the ground, use your portals to reach the other side of the gap ahead of you and wait for player 2 before you step through the force field into the final series of tests.
Player 1: Jump through the portals you made and the velocity and height will carry you across to the excursion funnel above player 2. Ride it to the end, step out, hit the red button up here (to release the blue repulsion gel out in the main area) and simply drop back down and both of you need to make your way back outside to the main area.