This is a PowerShell module for ServiceNow based on the JSONv2 web service:
https://docs.servicenow.com/bundle/tokyo-application-development/page/integrate/inbound-other-web-services/concept/c_JSONv2WebService.html
The JSONv2 web service does not require API access, it only requires the "ITIL" user role.
(Basically, if you can create/view tickets, this should work for you!)
Don't forget to change the ServiceNow Server URL at the top of the script before using!
#Username/Password authentication - Server is not needed if global Server variable is changed at top of script
New-ServiceNowSession -Server "******.service-now.com" -Username "admin" -Pass "pass"
#AESMP authentication - Defaults to Smart Card authentication based on Server URL
New-ServiceNowSession -Server "www.aesmp.army.mil"