Yes, you can use the 2S connector and just plug it into the 8 pin connector, assuming they are the same type. As you can see, the wiring is the same regardless of number of cells. For my 308duo, I just trimmed off the tab on the left side (tabs facing up) and plug it into the far right side of the 8 pin connector. Just need to make sure the negative on the balance connector is in the right place.

http://www.tjinguytech.com/_/rsrc/12...=117&width=200