how to design an X10-like multiple signals through 2 wires??

alright, here is my problem:

I have a Wii, and im trying to mod it so as to put a rumble into the wii remote's nunchuk. My idea is to tap two of the wires going from the wiimote to the nunchuk to signal the rumble (old cellphone vibrator) to turn on, and off.
Sort of an X10-type idea.

But i have no idea how to encrypt it so as it doesn't interfere with the wires regular uses.

Now, this is only in my head right now so could this for some reason not be possible?

Thanks,
-T