Add "ssh" to the end of /flash/cmdline.txt, after "quiet". Note that everything has to be in a single line and that there has to be a blank between "quiet" and "ssh".
You can also edit this on your PC, cmdline.txt is in the first (FAT) partition of the SD card. If you do this make sure the file is saved with unix lineendings, so eg use Notepad++ on Windows.
Or connect the RPi to some HDMI monitor and perform initial configuration there before switching to the problematic DVI cable setup.
so long,
Hias