How can I configure the Sage VirtualBox Appliance? [closed]

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I am working the with most recent Sage virtual box (ova) appliance, and I am trying to install LaTeX and all available kernels. I have been writing down exactly what I have done, which I plan to provide the community as a tutorial when everything is working. The problem is that I don't have a lot of experience with Linux, and so I'm basically hacking and slashing, as I can't find any documentation for how the appliance was configured or how to add LaTeX to the already-configured TeX install.

My question is, what's the best way to add functionality? Where should I install new things?

As an example: I wanted to start with LaTeX. Sage seems to have it's own environment with a working TeX, but it can't find pdfLaTeX for printing a notebook. I tried installing with yum, but CentOS installs an incomplete version that doesn't have a TeX package manager, so I can't add the missing LaTeX packages. I built LaTeX from source and it worked, but when I tried to install Ruby, yum installed the default LaTeX anyway, which then broke printing from jupyter using pdfLaTeX because it now found the one yum installed without the needed packages and ignores mine. I want to add pdfLaTeX to the preconfigured TeX environment in Sage so that Ruby and other languages can find it.

I'd build a box from scratch, but I cannot duplicate the functionality of jupyter notebook (where it comes up as a server for my host box) installing things from source, so I am trying to configure the pre-packaged ova, and since Sage is set up to be self-contained there, I cannot get things installed through yum to find the things installed in Sage. What am I doing wrong? Or was this not really something the ova was designed for?