click here for the firewire card and click here for the 6 pin to 4 pin adaptor cable. P.s. these are just examples and shopping around might get you them a bit cheaper. With regards to the extra two pins, they're there purely as a power supply and offer no function other than to draw power from the firewire port to recharge the batteries, (not always supported on some camera models) such is the case with the ipod, plug it into a 4 port socket and you'll get the connection but under the steam of the ipods battery, plug it into a 6 port and you get the added benefit of a connection whilst it gets recharged, and that's about it.
Err, hope that rambling helps.