You should be able to, I don't use FreeNas so I can't guarantee it should work for you, but this guide describes how to use docker with freenas: https://forums.freenas.org/index.php?threads/how-to-docker-containers.53972/
And this guide explains how to use docker for a litecoin node: https://github.com/salessandri/docker-litecoind
The benefit of using this docker image is that you don't need to install and configure the litecoin daemon, it comes preinstalled in a docker image. You just pull the docker image, start it with the command described in the link and docker then makes your computer/nas treat the image like a separate operating system that only has what it needs to run a litecoin node. When you start it it immediately starts the litecoin node and voila, you're done!