In the Configuration Parameters you can easily find out, how to get the parameter to use with the set_param/get_param command to set/get the information.
Therefor click with the right mouse button onto the information you would like to get via code.
Then you should see "What's This?". After clicking on it, a small help window will appear containing the information under the "Command-Line Information" section.
In the example above you would see the following:
Parameter: SystemTargetFile*Type:* character vector*Value:* valid system target file*Default:* 'grt.tlc'
So using the following code line will help you to set this config: