You should be able to just use the air bags to lift the suspension, then slide some dunnage underneath and deflate the bags. The cab can bend pretty easily, so make sure it's in a spot on the cab that can support the weight. Disconnect the torsion rod, then remove the brackets. Once you install the new brackets, connect a 2 inch or larger ratchet strap from the bottom left of the cab to the top of the exhaust bracket. Put some carpet or something between the cab and straps to protect the paint. Then you should be able to inflate the air bags to their normal setting(after raising it to get the dunnage out from under) and use the ratchet strap to move the cab back to the center. Then reconnect the torsion rod. If you need, you can raise the bags to release the tension on the ratchet strap, then disconnect it and lower the bags.