Hi Harm,
The Custom pool user is a feature for Indicium to synchronize to IAM or access a database under different credentials. These indeed can only be set-up via the 3-tier method. In this case using the Universal GUI.
The Software Factory is not fully supported yet for the Universal GUI but does already offer several screens. For instance, you can set the Custom pool user for the IAM Configurations.
We cannot make this available via Windows GUI without Indicium in between due to security of the credentials.
After setting up the Custom pool user credentials for the IAM Configuration, Indicium will start using those credentials rather than its own to connect to IAM.