If I had to guess, the macro would be:
/macro Attack "petcomall Attack Defensive$$petsayall <text>" and so on.
The problem with this is that it wouldn't have the Pet attack symbol.
Maybe if you have the pet attack symbol on your tray, then click edit and type the above command, it may work.
Warning: if others have "pet dialog" visible in their active tab, this will be spam: I'd ask around before using this too much (assuming it even works...)
Thanks, Zeh, I'll try some experiments. Leads much appreciated.
Bingo! And I can call out a single pet by name to emote the action, so that works. 
I see that there's an option to turn off the pet response text. I'm curious how many of you do, and if you're more likely to do it for some minion sets than others.
For slightly less noob fred, I'm wondering if it's possible to edit the response texts, or have customized just-for-me emotes displace them.