Start with the - end of the 7 pin:

1st pin (-) goes to - battery.
2nd pin goes to the small 2mm center battery plug.
3rd pin goes to battery +.
4 to 7 are empty in this case.

Like this:

http://media.hyperion.hk/dn/eos/HP-EOSOUT-CAR2-Diag.gif

It's available from Hyperion. Can't seem to find a Hyperion part number that I'm sure of, but here's a couple pictures/sources:

http://www.maxamps.com/HYP-MULTI-GOLD.htm

http://www.b-p-p.com/product.php?productid=107