Did find the information under "man wicked-config" (I think this is what i need) :

The functionality of wickedd can be extended through external commands and shell scripts. All of these
extensions are declared in server.xml, and all of them follow the same pattern.

Script extensions
Scripts are specified via the <script> element, which needs to provide a name attribute and a command
attribute. Again, the name serves as an identifier, while the command specifies the command to be
invoked. wicked comes with a (simple) parser for this, which splits up this command into a argument
array which is passed to execve(2) eventually.

An example would look like this:

<script name="install"
command="/etc/wicked/extensions/hostname install"/>

When defininig script extensions, it is possible to define additional environment variables that get
passed to the script. This mechanism is explained in more detail below.