Note that this also works if you're using a Jupiter, er, HSX-109 as your server, since the ARF file is laying loose on the Jupiter's file system just like it is on a Windows box. Of course, in order to put the ARF file onto the Jupiter, you either need a serial debug port (which only the developers and alpha testers have), or you need a USB keyboard to get a shell prompt on the Jupiter's screen and a copy of the ARF file on a CD-R so you can grab it.
Question: Isn't the ARF file just a TAR file? Aren't there Windows TAR utilities that could be used to edit the ARF file, too? I know that I have no trouble opening it in Winzip if I rename it to TAR. Dunno if Winzip can create a proper TAR that will work or not, haven't tried.