If you are replacing a worn clutch why do you care about heat or PB blaster?
Referring to Proboscis's picture, you want to spray PB blaster and apply heat around the shafthole of the flywheel/clutch assembly. When you got it nice and hot, use a couple of screw drivers and insert them under the geared edges to pray the entire assembly out.
Anyway, that is how I did and it worked for me.