You can try unbolting the lower control arm and then jacking the spring up into the car with it loaded in the lower control arm but I will say its not safe. Easiest thing to do is use an internal spring compressor. You have to position it correctly to be able to disassemble it inside the spring once installed and all the parts come out through the bottom hole of the lower control arm.
This is the one I have used in the past and you can "rent" them from parts stores. The end with the nut on it faces down so you can release the spring compressor once the spring is installed.
Now to do this without the compressor you can look at this thread over on the Corral specifically Post #4 but the OP ended up doing what I do: