Is anyone using the Custom HRMS function to connect to a system that uses SOAP API (I think)?

We're trying to get ADMP connected to Workday (the built in option only allows the connection to a single Endpoint URL, which means either HCM web service, or Student_Core web service).

I was looking into the Custom HRMS to try and set up two connections to the same Workday tenant but it is failing. Our Workday endpoint URL requires a username/password, and I don't see anywhere in the Custom HRMS to add that information. Also, I'm not a developer of any means, so the "header" and "parameters" portion is completely foreign to me, and the Manage Engine documentation is not helpful at all.