I have never used Composer so I asked the developer of Commonmark how to install his parser and he responded very promptly giving me some great pointers. At the same time I also found this resource which explained installing Composer on my host. I am now up and running and my previously converted posts work just as well with Commonmark.
I've been so out of the loop with open-source development but I am once again starting to have a profound appreciation for the community. These developers I've contacted recently have been great. Very friendly and knowledgeable.