I use rw cubes to make clones all the time.
Rapid Start from GH @ 5ml/ gal then pH to 5.6/5.7
Soak the cubes, I usually go about 1/2 hr or so....
I use some type of rooting hormone, clonex, life, rootech etc... to dust/dip the cut end
Stick 'em and wait
Keep 'em moist and warm
You'll need to water the cubes when they start to feel light
I use the exact same solution to water the cubes as I used to soak them
I have about 95% success, fwiw
I'll loose one every now and again but so has every other cloning technique I've ever tried

I was embellishing a bit when I said I get a 100% all the time, it feels like it though :)