hi
you could youse an analog multiplexer like described in tutorials thread. with that device you can send or recive a certain voltage, or a pulsed signal, or whatever via one wire to the ic where its spread (multiplexed) over up to 16 ch if you youse the 4067b for example. you need again 5 wires to controll the multiplexer.
its a serial technique, so if you run the controll programm very quick it seems to be same time.
if you combine them you'll have even more chs.
costs around 1,50 eur.
regards
woo