Install all of the new pulleys you have, including the water pump's pulley, and just do them as tight as you can without the belt on.
Not sure about other models, but on my VS, they are all metal pulleys, only my VR has a plastic tensioner pulley.
Install the belt as shown in the previous pics(my pics show the air-con set-up).
Upper left area-
Lower right area-
Use a 15mm spanner or socket, and push DOWN to turn tensioner pulleys center nut anti-clockwise, to slip the belt up over the top.
Once the belt is over and square on all of the pulleys, let the tensioner to it's normal position, belt is ready to go.
Then you can do a final nip up on the water pumps pulley bolts.