Hi mate, you can get the cable from any car audio store (eg. JB, strathfields etc.)
Shoudn't cost any more than $10.
You run the wire from the battery to the engine bay. You can run this where ever it can go (eg. under the carpet and through the firewall or what ever takes your fancy)
cheers,
Greg Kruse - GK Technologies
www.gktech.com.au