This from "Up Over"
Quote ".......on the longer straight part, a pair of locking- or water pump pliers (depending on physical strength/desperation regular Lineman's pliers might serve too...) and a thin object like a 4mm screwdriver to guide/lever the hook over the stub will do the job.
Probably easier with a second person helping by balancing the bike from the RHS since having the main stand at a 45° down angle provides the shortest distance/expansion on the spring, but I've also done it with the ST on its kick stand, whilst the angle of the bike is not really aiding the process.
A more helpful instrument can be found in most motorcycle workshops, a small transverse handle with a thin steel hook attached at its center (a 'spring-puller'), normally used to install/remove the springs/clamps holding the 'quick swap flanges/couplings' of moto-cross or race-track exhaust systems/silencers, or to handle the steel springs on the shoes of drum brakes (so most automotive suppliers/well sorted hardware stores should have such on the shelf); you'd need a short version though to have enough clearance towards the ground when extending the springs downward over the center stand stub (the procedure is to hang the short hook over the upper, frame sided stub and then pull the other end downward to get it on the stand's pin; for safety I again advise a second person securing the bike, and maybe a short piece of 2x4 underneath the center stand leg so it won't fold fully down during the work).
That small instrument would even permit to attach the two springs one by one, requiring way less force. "