Easy instalation with extroot. Prepare your USB (ext2, or other filesystem, just change the parameter of mount)
cat <<EOF > /etc/config/fstab
config global 'automount'
option from_fstab '1'
option anon_mount '1'
config global 'autoswap'
option from_fstab '1'
option anon_swap '0'
config mount
option device '/dev/sda1'
option options 'rw,sync,noatime'
option enabled_fsck '0'
option enabled '1'
option target '/overlay'
option fstype 'ext2'
config swap
option device '/swapfile'
option enabled '1'
EOF
/etc/init.d/fstab enable
cat <<EOF > /etc/opkg.conf
src/gz barrier_breaker http://d.wrtnode.com/packages
src/gz node http://wrtnode.3draty.cz
dest root /
dest ram /tmp
lists_dir ext /var/opkg-lists
option overlay_root /overlay
EOF
mkdir -p /mnt/sda1
mount /dev/sda1 /mnt/sda1 -t ext2 -o rw,sync,noatime
tar -C /overlay -cvf - . | tar -C /mnt/sda1 -xf -
dd if=/dev/zero of=/mnt/sda1/swapfile bs=1024 count=65536
mkswap /mnt/sda1/swapfile
reboot
opkg update
opkg install node-serialport node-socket.io
From Source
echo "src-git node git://github.com/majklovec/wrtnode-packages.git" >> ./feeds.conf
scripts/feeds/update -a
scripts/feeds/install -p node -a
make menuconfig
make -j13