Here's the best solution I've come up with. I'd like to hear yours.

Steady is the key. When the faery is in Steady, she will only cast embrace. Here's the problem, though: If you instruct the faery to use an ability, it drops her out of Steady and into Guard mode, where she'll start using abilities again. However, it is beneficial to ask your Faery to use Embrace, as there are many times when someone is between 71-99% health and you'll want the extra boost. For this to work, you must hit Steady after every command.

I have Steady hotkeyed to X, personally. Each exchange looks like this (for example):

1) Cast Rouse
2) Cast Whispering Dawn
3) Cast Steady
4) Cast Succor

If there were some way to macro your pet's abilities, I could create a rough solution to this by adding /petaction Steady at the end of every pet ability I wanted to activate, so it would reset. However, to my knowledge, there's no way to set pet abilities to a macro.