i don't believe your camera has built in firewire.
that camera records directly to dvd, correct?
the usb cable is only for picture transfer.
what you may have to do is record to the dvd.
put the dvd in you computer, and use a program like handbrake to convert the VIDEO_TS folder into an editable format (MPEG-4) which can than be imported into iMovie or FCP for editing.
http://www.versiontracker.com/dyn/moreinfo/macosx/21117