usb cd writer howto

1.build a kernel supporting usb cd

Device Drivers  --->

   SCSI device support  --->

   [M]   SCSI CDROM support

   [ ]   Enable vendor-specific extensions (for SCSI CDROM)

   [M]   SCSI generic support

2.install packages that do the cd burning

#emerge cdrtools

3.do the burning with cdrecord

say,I want to burn livecd-amd64-installer-2007.0.iso

#cdrecord -speed=4 dev=/dev/sr0 -v livecd-amd64-installer-2007.0.iso

and wait for it until finish burning