It will not be activated from a trigger, rather, some form of notification message when the bot encounters a certain condition. And I'd like everyone who is connected via dcc to receive it regardless of flags.
All established dcc/telnet/socket sessions are tracked in the "dcc" table (available to modules through the global export table). A simple example on how to extract information from this can be found by checking the source for "static int tcl_hand2idx STDVAR", which is found in tcldcc.c.