Back of the Lupos are very easy to do: 1. Jack up car and support on axle stands at the jacking points. 2. Support the rear beam/axle with a trolley jack. 3. Remove one bolt either side at the bottom of the shock. 4. Lower down the trolley jack until the springs come loose. 5. Reinsert new springs, the right way around and with the correct rubber seating attached (either old one if in good condition or a new one) 6. Raise the jack up supporting the rear axle, making sure that the springs seat correctly where they are suppose to and line up the hole for the shock for the bolt to go back through. 7. Tighten up the bolts and torque to spec (or use the 3 grunt method...) It really is painless, and if the bolts aren't seized should take you no more than ten minutes.
Mick's post in Replacing rear springs question was marked as the answer