I used the above stud method when fitting SSL's RS front suspension kit, on the first side at least. For the second I used a small scissor jack carefully located on the slightly loosened bottom kingpin nut to release spring tension in a fraction of the time, and as recommended by SSL. Found more control using studs again to compress new springs into place though.
BTW agree with Colin comments regarding the quite undramatic release of residual tension on main spring. Doubt if it was compressed more than a half inch on my Roadster once stub axle is resting on bottom mount. With regard to latter do support this or caliper itself to avoid strain on brake pipe flexy couplings when removing kingpin.
