Disco all shocks & sway bar WITH THE WHEELS LEVEL - don't mess with the sway bar if one end is higher than the other, ask me how I know...
get both front wheels off the ground a few inches, put stands under the frame somewhere. Jack one wheel higher, forcing the opposite side to droop. Put a stock bottle / scissors jack in place between axle and frame on the drooped side. Force it lower (not so far as to break anything...) and now you should have room for the new spring. Other way to do it is to actually sit on the brake rotor for that extra 2 inches or so, but that gets a little awkward and might qualify as "stupid".