Short answer: nope.
Capture as dv-avi then convert.
Why do you want them as mpeg-4?
DV-avi is much easier to edit.
Think of Firewire as a fancy serial port... a Firewire "capture" from a miniDV camera is simply a bit by bit transfer of digital data from DV tape to a computer file
As Ann said... use Firewire to transfer and create a DV AVI file (or, I think, a MOV file if you use a Mac) and then convert to whatever you need for viewing
I just wanted to say something as explicitly as possible that may not have been clear from what the others have said (though it's there in their reponses):
DV is a codec. It doesn't make sense to talk of capturing DV using a different codec. Sure, you may transcode to a different codec---but that's a step that comes after transferring the data in the original DV codec.