Replacing the rear springs is perfectly do-able at home, you don't need a lift or anything, but it's a question of the more you are prepared to remove, the easier it is.
You need to remove the seats to get to the front mountings, and access to the rear links is a great deal easier if you remove the petrol tank. I did mine with the tank in place, but it was a bit of a fiddle.
The hard bit is getting the bolts into the front eyes. Assembly sequence is rear links, then fronts, then U bolts. When I did mine I clamped a steel bar to the spring so that it projected forwards, enabling my wife to stand on. That gave me enough room to poke the bolt through the eye.
