This is related to this change. I have done the same on CentOS 5.4 and there are a few differences but essentially the modifications are the same.
The root.war file is on the same location and the change to be done is the same as in Ubuntu (remove the confidentiality requirement). The funny thing is that there is another file with the same content as the modified web.xml in etc/eucalyptus/cloud.d/gwt-web.xml but it doesn't seem to have any effect (modifying root.war is enough)
The Jetty connector change is a bit trickier, though. In this setup (I installed from RPMs) the Jetty configuration file (eucalyptus-jetty.xml) is not within the configuration files in /etc/eucalyptus but inside one of the Eucalyptus JAR files:
This file must be uncompressed, the eucalyptus-jetty.xml modified as in Ubuntu (replacing the HTTPS connector with and HTTP connector) and compressed back.
I don't especially like this setup since it makes it more difficult to fine tune Jetty not only for this HTTPS/HTTP change but also for some other connector parameters that you might want to modify in order to do some fine tuning.