how to use the live image?

["Jeremy C. Reed" <reed%reedmedia.net@localhost>]

I used the recent HEAD "live-image" target to create the 176 MB 
releasedir/amd64/installation/liveimage/amd64live.img.gz

The docs say "The live image is suitable for use as a disk image in 
virtual machine environments such as QEMU ..."

I uncompressed it (1409 MB) and tried to boot with qemu -hda 
amd64live.img.  qmeu needs it to be writable so chmod u+w. It boots the 
boot loader. The kernel mostly boots. But then stops at:

boot device: <unknown>
root device:
use one of: re0 wd0[a-p] cd0[a-p] ddb halt reboot

I tried wd0a and then wd0b for swap. I tried generic file system, ffs, 
cd9660. I tried booting with -fda and -cdrom but these won't even boot 
the loader.

Where are the doc and examples for booting this image with qemu?

Thanks