Question:
What is the command used to configure IIS via Symantec Installation Manager (SIM) if those components are not present?

Answer:
The following command (run it as Administrator from the command prompt) can be used to install manually the IIS components needed for the Installation Readiness Check in SIM:

servermanagercmd.exe -install web-server web-asp as-web-support web-mgmt-compat net-http-activation net-non-http-activ

•Set server up for installation

–Servermanagercmd.exe

•Web-Server
•Web-Asp
•AS-Web-Support
•Web-Mgmt-Compat
•NET-HTTP-Activation
•NET-Non-HTTP-Activ