wget http://archlinuxarm.org/os/ArchLinuxARM-trimslice-latest.tar.gz
dd if=/dev/zero of=arch.img seek=749999999 bs=1 count=1
mke2fs -F arch.img
sudo mknod /dev/loop1 b 7 0
sudo losetup /dev/loop1 arch.img
mkdir arch
sudo mount -t ext2 /dev/loop1 arch/
cd arch
sudo tar xzf ../ArchLinuxARM-trimslice-latest.tar.gz
sudo dd if=arch.img of=/dev/sdb1 bs=8M