Hi Charlie,
Scott is the ultimate expert in everything-ribbon-workbench, so he may have other suggestions.. but, it seems, you’ll need to create a custom button, hide the default one, and, probably, use javascript(customrule) to disqualify the leads. Or you can use a dialog as mentioned in the post below, but I’d rather do it with javascript(can be combined with a workflow.. add a hidden field, set it to true, then call Xrm.Page.data.save from javascript.. and register that workflow on save)
