Hi Col,
I guess you know that you don't need to remove the springs to drop the motor and subframe in one go. But if you need to remove the springs for other reasons I recently rebuilt my subframe and I used long 10mm threaded bar. Its a slow way but SAFE - I removed a bolt each side of the inner pivot bolts/arms (there are 2 each side). Replaced with the threaded rod and slowly undid the rod and existing bolts.
If you want to do it with subframe and wheels still on the car then you do it with the car on the ground and place a trolley jack under the lower wishbone and then undo the rear pivot arms/bolts ensuring that you have enough clearance. Some might use a bottle jack. The spring uncompressed is around 280mm from memory plus the rubber rings add another ~25mm,
Rgds, Joe