Setting the content key of a text label using an "onCreate" script

Hi OpenText-forum,

after doing some research I could not find any documentation or advice on the following topic, therefore I am opening this discussion.
In a report design I have a text label that is localized using properties files. The key to read out the localized value is entered as content key, please see the first screenshot.
Now I would like to set this content key based on a value selected on the parameter screen. So far I only know how to show a certain text in the text label by adding the following to the "onCreate" section of the label: this.text = params["TEST"].value;
Is there something like: this.contentKey = "Here stands the key";?

Thank you very much