I'm not sure if I understand your question exactly, but you can write a plugin to listen to a new route (URL endpoint) or interprocess communication and load and call NodeBB libraries.
You may consider using this plugin Git repo as a bootstrap to get you started quickly. Remember that the plugin.json, package.json, and library.js are the first files to work with. The plugin repo name / directory name will need to match the glob nodebb-plugin-* and it needs to be directly under the node_modules/ directory which is at the root of your NodeBB directory.
A new post in topic shows only when page is refreshed
In my topic.tpl I made some changes using @first to separate first post in topic from others. It worked, but there is now next problem. When i create a new post it doesn't show it instantly, I have to refresh page to see that post.
This is how my topic.tpl looks now http://pastebin.com/jYNQ1WVr
Also, I noticed this http://screencast.com/t/jESEIi9GiY . Instead of just creating one more <li> in .otherPosts div it creates another .firstPost and .otherPosts div.
I think that maybe I made some mistake with using @fist but I can't figure out what is it. Someone help?