I've done it without one, but only if fitting lowered springs. With the car on the ground, remove the top nut, the metal plate, then the nut under that. Slowly jack the car up until the spring is loose. Then remove the strut as per normal.
If you are not fitting lowered springs, you will need compressors to get the spring back on. Otherwise you can push the spring down enough to get the nut on when fitting lowered springs.
springs under tension can and will kill you if something happens and they are not contained. dont be cheap. get a pair of spring compressors for about $50 from most auto shops. very very risky not using them.
I agree,very dangerous to try to remove/fit them without spring compressors,a spring has a lot of energy stored in it when its compressed onto the strut,and as mentioned,more than one person has been killed before trying to remove/fit springs without the right tools.