As the api is now able to set article badges [1] there should be an api that enables this funcionality. There is already a mockup [2] which shows a possible solution. It should be mentioned that currently all items can be a badget of a sitelink.
[1] https://gerrit.wikimedia.org/r/#/c/82637/
[2] https://commons.wikimedia.org/wiki/File:Site_link_badges_edit_interface.png
Version: unspecified
Severity: normal
Whiteboard: u=dev p=0 c=frontend
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=56693