its my understanding that you dont need to hit shield bash to get the 10% damage bonus. taking the talent just passivly gives you 10%. I was hitting shield bash then shield block and SS manually a lot until i asked around
When you hit shield block its important to only use abilities that can proc sword and board.
so the macro is
/cast shield block
/use 13
then manually hit shield slam. It used to be /use 13 /use 14 but you cant pop both autoblockers at the same time