I took a cut off tool to a 19 mm socket and put two "windows" in it. Worked like a charm getting them off. To get them back on i will just weld my "sst" to a c-clamp.
I normally use a 1 1/2" PVC pipe that has been ripped open slightly above the end to form a rim. That way you have room to compress the valve & install the retainers through the open area.
the actual SST is a hand operated lever that bolts into place. it just takes longer with the SST because you have to rebolt it down for every cylinder's worth of valves.
Once you've had alittle practice, it's just faster to make your own tool & do it.
and it's not hard at all. Especially removing them. and ESPECIALLY if the heads are off the engine.