Hi @ShepardEG,
No no, I understood you before. 
The link I shared contained a discussion about which directory to include startup applications. I've linked it below:
Assuming your work must also involve having the file in one of those directories, I figured it might come in useful for you.
While it is pretty straightforward in its intentions I agree that the build documentation does a pretty poor job at explaining which parts do what, so developers can edit them as needed.
While I think most of the pre-installed apps (at least when it comes to the webOS TV version) are QML Native apps, pre-installing webapps should, in theory, work fine.
I'm going out on a limb here and will say having pre-installed web apps would involve finding out which directory they reside in (upon regular installation) and then maybe editing the build scripts to include your .ipk within the earlier identified directory.
In any case here's the link for the Yocto project documentation regarding image customization.
Please note that I'm not a platform developer so unless someone from LG verifies the above there's no guarantee.