Exactly. Even if you could, activated items won't work because the client will just say they don't have it when the player hits their use item / use taunt button. It
might be possible to trick it if they have a taunt equipped (say, Director's Vision), but since I haven't actually tried it, I couldn't say.
FlaminSarge being the person you're talking about.
Now, as for taunts... every line of dialogue and taunt in the game has an associated
VCD file packed in
scenes.image. Unfortunately, their filenames are numbers. For instance, looking at talker/demoman.txt, the DemoMan calling out "Put a teleporter here!" is "scenes/Player/Demoman/low/968.vcd". Taunts aren't in the talker files as they only include the ones played by the game's
response system.
VCDs can be viewed with FacePoser which comes with the game.
In theory, a
logic_choreographed_scene / instanced_scripted_scene (likely the latter as the former is intended for mapmakers) entity can be used to play taunts... but you need to know the appropriate vcd and the appropriate inputs to send to it. I imagine for Conga, you'd just need the player, but for, say, RPS you'd need at least two arguments for the players.
Incidentally, each class would have their own VCD for multi-class taunts... chances are things like RPS would actually have have something like 9 classes * 9 classes * 3 choices * 2 choices = 486 different VCDs. It'd be more if they allowed both players to have the same one.
Edit: I may try to
collect some data on taunts after work tonight. I have 10 of the 15 taunts from this update (including an unusual I should probably sell soon since it's still at like 6 buds).