If your IAM user account doesn't already have Access and Secret Keys you'll need to create them here.
Then create a profile
Writes a new (or updates existing) profile with name "myProfileName" in the encrypted SDK store file
Set-AWSCredential -AccessKey akey -SecretKey skey -StoreAs myProfileName
Checks the encrypted SDK credential store for the profile and then falls back to the shared credentials file in the default location
Set-AWSCredential -ProfileName myProfileName