turn off power supply, pull out battery, press D+B , hold and insert battery. Login as root,
mkdir -p /mnt/xxx
mount /dev/mtdblock3 /mnt/xxx
cd /mnt/xxx/root/Documents
and copy your file to inserted CF or SD card.
if you use one big root partition, mount mtdblock2:
mount /dev/mtdblock2 /mnt/xxx
cd /mnt/xxx/home/root/Documents