Ok, the "best" overall way that I have found so far is to give it an active sonar sensor and delete the ping sound from the sfx.agg so that it is reported strictly by the Active Intercept Autocrew.
Now this has a big problem associated with it. The game sound engine is constructed in such a way that subs, ships, and torpedoes are assigned their own ping sounds that can be edited individually, and then everything else left over gets assigned the generic ping sound. SO... deleting the ping sound for the missile also means no ping sound for any helos or buoys... which is a BIG BIG "hell no!" for doing it this way.
I also am beginning to agree with molon... how big of a pain in the ass would it be to hear a pinging every time you launched missiles. Yikes!
So, the only way left to go is to try to add some kind of TIW (which is automatically not reported to the launching platform, even if the torpedo is launched by a weapon launched by the launching platform)... and this means getting messy. You have no idea how hard it is to try to get missiles to launch torpedoes at nothing!
:p