You would add them the same way you add a server with a GUI. Assuming you are uing the Agentless Management option, you would configure your iLO as required for AM and then add the iLO to HPE SIM. The trick being getting the AMS installed on the server for full functionality. I run these commands to install the HPE Service Pack on Server Core (which you can put into a PowerShell script or batch file) since web browsers are not available on Server Core:
C:\PathToYourServicePackFiles\smartupdate.bat add /baselines C:\PathToYourServicePackFiles
C:\PathToYourServicePackFiles\smartupdate.bat add /nodes localhost type=windows
C:\PathToYourServicePackFiles\smartupdate.bat inventory /nodes localhost /baselines C:\PathToYourServicePackFiles
C:\PathToYourServicePackFiles\smartupdate.bat deploy /nodes localhost
C:\PathToYourServicePackFiles\smartupdate.bat shutdownengine /force
In my case I have a custom baseline library that I built that includes, among other things, the AMS package.
Hope this helps.
NK