Slotted nut, if you're not keeping the old coilovers then just clamp the damper with maul grips and undo. As for tightening them 22mm ish(?) socket clamped in maul grips with an allen key in the top to stop the damper spinning, bit of a fiddle but has served me well on corrados and golfs alike.
Lower bolts as mentioned previously, solid breaker bar with scaff bar extension on it if an impact gun isn't handy, wire brush threads, decent penetrating oil, car solidly supported so you can apply some force.
It also helps if you have purchased these in advance....
