I've been told that if you use a PAL minDV cam and hook it up to a NTSC miniDV cam (thru camera dub). That you can achieve a fairly decent PAL to NTSC conversion.
DV cameras don't do any conversion to firewire signals - in fact in dub mode they are dooing nothing but transferesing a data file from one tape to another, they will tap off it to output the image to the viewfinder/LCD, but that's it. No conversion, sorry.