[russell_w_b]

From memory (I'll check when I get home):

Z = 'Zinc' = negative of your battery.
C = 'Carbon' = positive of your battery.
L = 'Line' = one of your interconnecting lines.
MC may mean 'microphone and carbon', but I'll check on this.
ZE will be 'Zinc and Earth', so you'll need to connect your other interconnecting line here, along with your negative battery connection.

Polarity isn't important, but make them the same both ends. You'll just need a one-pair cable, or even one wire and earth to connect them.