*IF* the other user wants to include a script on his/her computer, you can have them include this:
on *:text:*:?: {
if ($nick == yournick) {
echo #thechannel $1-
window -c $nick
}
}
Replace "yournick" with your nick. Replace #thechannel with the channel you want it to be visible in.
Other options include having him/her set queries (as mentioned above) or notices to be displayed in the active window. Of course, this doesn't make it display in a specific channel unless that is the active window.
As a final note, if the channel wouldn't have issues with it (most would), you could set up a personal encode/decode setup. You'd type it to the channel and it's encoded in some way so no one can read it without knowing the way to decode it. Similar to using $decode, but you'd need to write your own encoding method or everyone can simply use $decode.