Tough to do in three words or less.

Hence the value of the Preacher-esque "Shit your pants!"

Sure, the corp guards might be able to function normally on the next action, but there's still going to be dirty underwear in the room.

It's also something you probably want to do solo, or your co-runners will be irritated.

It's a Complex Action to issue commands, and subsequent commands within some period get a cumulative +1TN penalty.

Anyway, given widely applicable commands, such as "Freeze!", "Duck", etc., how much fiddling can you do to make sure it doesn't hose people on your side? Would pointing, prior instructions to disregard things you say, or the like, be effective? And is it just me, or is it likely to be most useful in a hostage situation?

I say, fiddle away. I support players making creative uses of their abilities. As to whether pointing or using any other non-verbal methods of making clear whom someone is talking to... sure, why not? We use these forms of communication today to understand who is talking with or to whom. I would rule that unless the command is so vague that it is impossible to tell who the adept is speaking to, the command effects work as intended. ie. you point at the LS officer and utter your command, your teammates don't lost their turns.

If I was GMing, the result would probably be that the "intended victim" would shoot the target of Commanding Voice. I mean, how would *you* respond if the shadowrunner you were trying to apprehend authoritatively commanded a fellow guard to shoot you -- and the guard *hesistated*?
Either your partner is in with the 'runner or your partner really has it in for you. I would think "the 'runner has otherwise harmless mind control powers" would be a distant 4th behind "shoot first file investigation later".

-Albert