I've always wanted to do that! It probably will require insane teamwork and a good map where the enemy cav won't spawnrape though. For this you really have to be on teamspeak and you have to be really fast!
1st guy spawns 1 construction site + 1 material, 2nd guy spawns 4 material,
the rest spawns siege shields and stacks to troll the cav, maybe some heavy infantery would be cool too to protect the construction site.
And nice banner!