Hi Costa,
For CMS pages you can currently disable the friendly urls by adding this to user.config:
<add key="UseUrlReWriting" value="false"/>
In the next release of mojoPortal (coming this week), it will also be possible to disable freindly urls in the blog by adding this setting:
<add key="Blog:UseFriendlyUrls" value="false" />
Hope it helps,
Joe