Instead of using the system.xml to create groups and sections in a static way I want to create a section and groups in the code. Pls take a look at the screenshot:

Whats shown on the screen was done in the modules system.xml, now I want to do that directly in the code. I also found the place where the form is being built, its in app/code/core/Mage/Adminhtml/Block/System/Config/Form.php in the initForm() function. There it reads the sections and the inner groups. The problem I have is, that I dont know how to proceed from here. Maybe somebody has done a similiar thing or can point me in the right direction. I guess part of it is creating a Mage_Core_Model_Config_Element by myself?