Hi Eric R,
thanks for your reply.
Unfortunately the users won't be able to know the value of the paramter to be added to the href. Therefore I was trying to add the parameter programatically "onclick" of the checkbox in question.
Although this might not be best practice, but is there a way to add a new "nodeAttribute" (or what ever they're called internally) to the editor, which I could include into the module NodeInspector using the hack referenced in the previously mentioned articel, like so:
Telerik.Web.UI.Editor.Modules.RadEditorNodeInspector.prototype._nodeAttributesArray["A"] = [
// the default ones for an a-tag/link
"href", "target", "LinkManager", "id", "title", "className",
// my custom checkbox
Thanks again for your help.