To inlcude NoDogSplash into your OpenWRT image or to create an .ipk package (similar to Debians .deb files), you have to build an OpenWRT image. To build the firmware you need a Unix console to enter commands into.
Install the dependencies of the build environment (Debian/Ubuntu):
sudo apt-get install subversion g++ zlib1g-dev build-essential
sudo apt-get install git libncurses5-dev gawk gettext unzip file