Setting Organization FormLogin options programmatically

Hi, community!

We have a Java extension that's creating a bunch of TW entities programmatically, among others a organization entity. Creating the organization entity, adding members to the organization, assigning permissions and setting the home mashup works as planned, but how does one set the FormLogin options programmatically? I'm talking about login prompt and login image, among others, that are editable through the Composer (see image). I've checked the API docs at http://support.ptc.com/help/thingworx_hc/thingworx_7_hc/ThingWorx_Core_Help_Center/baggage/javadoc/com/thingworx/security/organizations/Organization.html but couldn't find suitable methods.

We're using TW 7.3.4.