I cleaned out as much as I could using a Q-tip and a lot of it flaked out.
I made sure no cotton fibers were left behind. Put the new plugs and springs in, and so far the car is driving smooth. I don't feel any misfires, but my scan app (Torque Pro, using a bluetooth OBD) says it picked up 1, 9, 0, 1 misfires on cylinders 1,2,3,4 respectively. I don't know how accurate that thing is, but it feels fine. I'm going to monitor it as I drive more and will order a new coil rail soon.
You could also use electronics cleaner, or isopropyl alcohol 90% or higher. Don't use the standard stuff thy is only 70% alcohol as it has more contaminants than purer alcohol and will not dry as quickly
Carefully twist the boot off the coil which will free the spring. Then just sandpaper or lightly file the corrosion off the contact points, spray with some electrical contact cleaner, spread the spring out just a tad, replace and be done with it!