Is there a way to pass-thru current default credentials to powershell SPML request to ARS?

We use PIV cards for end user authentication. Our default credential can be used with runas.exe or right-click over internet explorer to launch the browser with privilege.

With powershell, we launch the shell from an elevated prompt - again using 'runas' in order to trigger the credential tile to pop-up allowing selection of PIV card with username hint.

for powershell SPML, I'm prompted for credentials … but not using the PIV tile. 

Question - is there a way in PS> or SPML to default credentials to the ones used to launch the shell calling the script?