Autoloader was added in AutoCAD 2012 to simplify the deployment of AutoCAD plug-ins, and is extensively used by apps in the Autodesk Exchange Store. (You’ll find several articles about the general Autoloader features on Kean’s blog).
We introduced a few enhancements to Autoloader in AutoCAD 2013. One of which was the StartupCommand parameter. Use this if you have a plug-in that loads on AutoCAD startup and you want it to run a command as soon as its loaded. The benefit of using a StartupCommand is that the entire AutoCAD UI should be loaded when the command runs - which isn’t always the case when you run initialization code by implementing IExtensionApplication.Initialize in your plug-in.
Here is a Components section from an Autoloader PackageContents.xml that causes a command called RunMeFirst to be invoked at startup for AutoCAD 2013 or any AutoCAD 2013 vertical:
<RuntimeRequirements OS="Win64|Win32" Platform="AutoCAD*" SeriesMin="R19.0" SeriesMax="R19.0" />
<ComponentEntry AppName="ADN_StartupCommandTest" ModuleName=".\Contents\SimpleTest.dll">
<Command Local="RunMeFirst" Global="RunMeFirst" StartupCommand="True" />
To try this, download the sample bundle from here and unzip it into your %appdata%\Autodesk\ApplicationPlugins folder. The next time you launch AutoCAD 2013, it will run the command – which simply prints “Hello World” to the command line. (Note that the sample DLL is built for AutoCAD 2013, and the PackageContents.xml restricts loading to AutoCAD 2013 only – this is because StartupCommand was only introduced in the 2013 release).