At the bottom of this page, there are some general example projects (C#) to make plugings of your own.
To demonstrate a custom plugins here is an example to setup lslint for LSLEditor.
1. Create a subdirectory named plugins in the directory where LSLEditor resides.
2. Get lslint.exe form http://w-hat.com/lslint and copy lslint.exe in the just created plugins subdirectory.
3. Start LSLEditor, menu Tools - options - Environment - Plugins
4. Check the checkbox to use lslint and hit Ok button
5. For using lslint, hit menu Tools, on the dropdown, there is lslint
If you want to write your own plugin, there are two templates in C# code,
which has to be compiled in Visual Studio or Sharp Develop (the last one is free).
Installing the plugins in the same way as lslint.