I've always thought that chain push scores are damn cool but I have never tried one myself. Now is as good a time as any to start as I have a mv7 player so I have been trying it out. What I came up with is a way to push the ball carrier 4 squares using 5 blocks and 1 GFI (assuming mv6 on the GFI guy) with 9 players. This is probably a standard way of doing it but here is the method anyway.

This same technique works with a spread out defence, just replace the top blue player with an additional red player. This does mean using 10 players which leaves only 1 back to pickup and pass the ball. However there is a player left unused at the end of the push who could help with getting the ball to the carrier.