My strings of GE Color Effects are quite old - purchased in 2010.  Evidently in the past couple of years, they have changed the lights to a style which is not hackable.  The new lights have 2 wires per bulb/pixel (one in, one out), which provides power.  This is similar to how cheap old incandescent or even non-controllable LED strings are wired.  Each bulb/pixel is hardcoded with patterns (rather than sending commands down a single-wire-interface real-time) and thus isn't hackable.

So if you can find the old style with 3 wires in and 3 wires out of each bulb/pixel, go for it.  There may be a 5 wire version which adds AC passthru for connecting strings end-to-end.  But the new ones won't work with this system.  

That's too bad.  I was really hoping to buy 2 more sets and have lights on the front and back of the house that ran matching custom patterns.  Maybe I can find some old ones used somewhere.

Good luck!