mrw + packet writing + variable packet sizes

Hi guys, Is it possible to do packet writing of variable sizes? I've applied the mrw patch to my kernel as i found on the site, but the only way it seems I can create a usable disk is if i use pktsetup with the -q option. Is there a manual way to reserve a track & say format it with ext2 or so? also what exactly is mrw? :) Regards Nigel