The end for the 2S Zippy is correct (Zippys and HK/HC lipos in general use the JST-XH type (which is also called the Align style) balance conn. I'm not totally sure the charger end will plug into your BC-6. I'm guessing it would, but don't know for sure.

The other way is to get an adapter that plugs into the Zippy balance conn and converts it to the same style as your 3S lipos, but I don't know which those use. It =would be like one of these -

http://www.rcaccessory.com/Hyptoalign2s.aspx

But using the type balance conn your 3S uses. This guy is a Bantam dealer and has adapter boards for the BC-6 too,