In my mind, you'll need to remove the springs no matter what - and potentially roll the rear-front ends out from under the car so you can actually have access to work on them.
If your car has the older pressed in bushings (steel shells), they are NOT each to replace while everything is in the car. It is tough getting the old ones out (usualy requires some creative slicing/dicing) - and you can bet you'll need to do it on the front/rear spring perches as well. Not trying to rain on your parade, just being realistic.