Damian,
If they are defined in as Initial Parameters, then you can get them using the getInitParameter() method.
example:
static
String LIST_PAGE = "ListPage";
String page = getInitParameter(LIST_PAGE);
portlet.xml excerpt
----
< !-- example of an init parameter<br /> init parameters should be used if there is configuration<br /> used by ALL instances of the portlet on your server <br /> it should not be used for instance-level parameters<br /> -->
<init-param>
<name>ViewPage</name>
<value>/WEB-INF/jsp/view.jsp</value>
</init-param>
<init-param>
<name>ListPage</name>
<value>/WEB-INF/jsp/list.jsp</value>
</init-param>
----
Cheers,
Mike