Have a look at the thread at
http://discussions.apple.com/thread.jspa?threadID=1422086&tstart=26 batman's Frog.
The most promising answer there, from "baileybird", is:
"+have an IMAC Desktop 10.4.11 and yes the JVC GZ-MG330 does work with IMOVIE 08, just don't follow the JVC Manual+
+Connect the Camera to the PC as per their instructions+
+Select "Playback on PC" on the camera+
+Then an ICON will appear on the desktop called "EVERIO_HDD"+
+Then open IMOVIE 08 the software automatically attempts to import the files and you get a prompt on the screen to "IMPORT ALL" or the files you wish to import. Follow IMOVIE prompts from there - not the JVC brochure.+"
But there are some other suggestions, too.
Cheers
Rod