Thanks for your suggestion James. Annoyingly, the route prefix that I would have liked to match (the one for the LNBlog Add-on) appears to be called on every page, so this isn't going to work. However, I think I can just look for the "/blog/" in the URL, so that is not a problem.
The problem I am having is actually changing the page style (and, once I've found that, knowing when to change it). Perhaps this is a really simple request, but I am relatively new at XenForo and I can't find the method/variable I need to call/change.
If it is the case that whatever method/variable I need to call/change is accessible in any Code Event Listener, then I can obviously change it in whichever Code Event Listener is called first.
Perfect. I think I stumbled upon this before and forgot about it. Is there any way to access the controller from a Code Event Listener though, or is my only option to manually edit the Add-on code (every time it is updated)?