You will want to know C/H/S values for your destination media ahead of time with growimg.sh.
Slow write method for a 1GB CF with 1986 cyls, 16 heads, 63 sectors:
gzip -d flashimg-20090227.GENERIC.console.gz
./growimg.sh 1986 16 63 flashimg-20090227.GENERIC.console
dd if=newimg.1234 of=/dev/sdXc bs=126b
Fast write method for a 1GB CF with 1986 cyls, 16 heads, 63 sectors:
gzip -d flashimg-20090227.GENERIC.console.gz
./growimg.sh -t sdX 1986 16 63 flashimg-20090227.GENERIC.console
gzip -d flashimg-20090227.GENERIC.console.gz
dd if=flashimg-20090227.GENERIC.console.gz of=/dev/sdXc bs=126b
gzip -d flashimg-20090227.NET45xx.com0-19200
vnconfig svnd0 flashimg-20090227.NET45xx.com0-19200
mount /dev/svnd0a /mnt
cd /mnt/etc
vi rc
cp /local/nsh/nsh /mnt/bin/nsh
mkdir -p /mnt/usr/local/bin
cp /local/nsh/save-ro.sh /mnt/usr/local/bin/save.sh
chmod 0755 /mnt/usr/local/bin/save.sh
umount /mnt
vnconfig -u svnd0