In one of my portlets I needed to have edit icon, and in onclick action it shows my own page. "edit.jsp"

so in portlet-ext.xml add

<init-param>
<name>edit-action</name>
<value>/ext/updates/edit</value>
</init-param>

and

<portlet-mode>edit</portlet-mode>

In jsp you could manage it via actionResponse.setPortletMode() but
because IceFaces doesn't allow you to catch actionResponse(expect
processAction() Method), you could manage it trough another way like
javaScript.Hope this code  help you(use it in your commandButton):
submitForm(document.hrefFm, URL);
which in URL is your currentURL expect that you change  your portletMode
or something else.