Reportedly, you can cast a freezing trap while in combat by spamming this macro:

/script PetPassiveMode();
/cast Freezing Trap

Any confirmation?

I'll give it a try tonight in Z'G and let you know.

Original poster says it only works in PvP so ZG won't be a good test.

According to a guildmate hunter, it only works in PvP if you are attacked first. He's still having fun with it, though, as it's a nice way to freeze trap somebody and save your feigndeath-freeze trap combination for later.