To be sure you understand: This workaround will leave the (encoded) password in the "startinfo" for that process until it's closed -- so anything on that machine can read the password (and probably decrypt it).
$userADPW = "password"
$userAD = "john"
$servip = "Server2K81.homelab.com"
$PassSec = ConvertTo-SecureString $userADPW -AsPlainText -Force
$credentialPS = New-Object System.Management.Automation.PSCredential ($userAD,$PassSec)
Start-Job -ScriptBlock {
param($psip,$CredentialPS2)
Start-Process powershell -Argumentlist '-noexit',"&{
`$Credential = New-Object System.Management.Automation.PSCredential '$($CredentialPS2.UserName)', (ConvertTo-SecureString '$(ConvertFrom-SecureString $CredentialPS2.password)')
Enter-PSSession -ComputerName '$psip' -Credential `$Credential
}" -passthru -Wait
} -ArgumentList $servip,$credentialPS