Step 1: Find a cord about 2-3mm thick, roughly 500mm longer then the perimeter of the windscreen to make it easier for yourself.

Step 2: Run the cord inside the seal, leave the excess at the bottom in the middle. Place seal on your windscreen.

Step 3: Place the windscreen in place, and get someone to give you a hand (sometimes with a brand new rubber it can be a bit tough). Get your helper to put a little bit of pressure where your excess cord is

Step 4: Have the excess cord on the inside of the cab. While your helper puts a little bit of pressure on the windscreen, slowly pull one side of the cord sideways and up on itself. Hopefully this should open the seal up enough for the windscreen to fall into place.

Step 5: Continue, slowly pulling, bit of pressure, and hey presto the windscreen should be in.

Hope i explained it well enough. =]

And it feels so awesome to have it getting finished. I literally jumped up and down like a child before christmas, needing to go to the toilet, on red cordial. True story...