Does the United States Government Configuration Baseline allow for IIS Express installations as part of a software install (self-contained in the user's home account)?
Is there a waiver process?
Respectfully disagree that policy discussions are offtopic for Information Security. Good information security starts with good information security policies.
IIS is a prohibited install on workstations under USGCB. This would suggest that any waiver must be based on a business case and approved by your agency's Designated Approval Authority as part of the Authority to Operate for your Major Application or General Support System.
Refer to your agency's security policy documentation and the NIST website.