I can try to outline how I would do it with a custom script, though I
have to say, custom attributes are not recommended, you should either
use the "data-" prefix or introduce a separate namespace with a linked
DTD.So I assume you have a rule that get's triggered when this button is
clicked.In the "Set Variables" action within the custom code you can
access this button "event.target". From this you can access the
attribute by name "event.target.getAttribute('cst-text')" and apply it
to an eVar o...