You can do it like you said, just undo the 2 bolts holding the clamp to the subframe, two nuts holding the steering rack line to the clamp from the engine bay and slide the bush out. It might be a bit fidgety but if you can slide the bush towards the driver side it might be easier because the steering rack is thinner towards the driver side than where it sits when mounted.
I only dropped my subframe because I was fitting my antiroll bar at the same time, but even so didn't have to support the subframe after unbolting it.
