Overtake it immediately on the right hand side. Then take the lane in front of the bus and commence trackstand. Watch out for buses though. They are a bunch of *****es. Truckies generally are good blokes who know how to handle a large vehicle and are appropriately trained. It would appear you can pick up your licence to drive a bus from your local 7-11 in Melbourne.
Must be a different species here in Sydney. I had a waste paper truck jump left without looking from the middle lane into my path in the Transit Lane on Wednesday and I only just managed to squeeze past on the left and avoid ending up in the hopper bin at the back. Then they tailgated me. Buses are much more predictable where I live.