ZCA hints

Customize view without touching the original template

    <configure package="original.package.browser">
        <browser:page
            for=".something.ISomething"
            name="my_view"
            class="custom.package.browser.view.MyView"
            template="my_view.pt"
            layer="custom.package.interfaces.ICustomPackageLayer"
            permission="zope2.View"
        />
    </configure>

with zcml <configure> directive you can override a browserview without touching its template (for example if you want to override only the class or the permission).

for for and class attributes you nedd to provide the full dotted name of classes of custom package, and let the template path as is (Plone will search it into the original package).