Hello csuzw,
I’m afraid WoW macros can’t detect as you wish.
You might be able to import them as a second macro with pause/wait feature and pause them down in between, but I am not sure if they will fire correctly:
Best option it would be to have it as a modifier and keep a tracker of when to use them:
/cast [mod] 14; Berserking
or
/cast [mod] 14 /cast Berserking
/cast [mod:shift] 14 /cast [mod:alt] Berserking
Hopefully that helps