Friends,
I have done with DC volt step-up, and posted the story here;
(I am sorry it is in Thai but I think you could follow it - Google translation could help - with around 80% correctness :))
http://www.forum.munkonggadget.com/detail.php?id=141852
In fact you can use 12 VDC from car to charge the 3rd gen ipod directly as well.
Pamalee
== Update ==
Hi oldturkey03
''Eliminate firewire charger complication with USB 5V ''
It is the DC Volt Step Up ( appox. 9 USD from e_bay)
http://www.ebay.com/itm/400601163750?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
For 3rd Gen
- See pinout for 12 VDC +,- from the below link
http://pinouts.ru/CellularPhones-A-N/iPhone_connector_pinout.shtml
I use pin 19 for +12V and pin 29 for –
If AC-usb adaptor is used, it should be at least 1 Amp. to keep charging time similar with the original firewire charger. (P=IV)
This one can also apply for IPOD 2nd GEN as well. Just seek for the 6 pin firewire port for it.
This is is my stuff --http://upic.me/i/qh/usbchargeropidg2g3.jpg