I'm posting this in the hope that it helps people. I've just started down the road getting XBMC going and I'm amazed at helpfulness of the community. I hope to contribute here in my small way.
I've created a patch file to automatically apply the necessary code changes the ViewType_Multiplex.xml file after an git update is downloaded for aeon or you download a version for the first time.
I just downloaded the latest version of Aeon Auriga as of 5/30/2009. I followed the instructions on the first page of this thread and I made the changes to the ViewType_Multiplex.xml as instructed. I then created a patch file so that I can easily re-apply the code changes back in when ViewType_Multiplex.xml is overwritten in an update. If you're running on OS X/Linux, the patch command is built in. For windows users, there is a port of patch that you can download. I will include the instructions for OS X. I assume the windows version will be similar. Here is the what you need to do:
1. download the needed files below into the 720p directory:
http://www.dreamht.com/aeon/mods/multipl...Plot.patch
http://www.dreamht.com/aeon/mods/multipl...exPlot.xml
2. open up a terminal window (OS X: Applications/Utilities/Terminal)
3. change into the correct directory by typing this into the terminal prompt:
cd Applications/XBMC.app/Contents/Resources/XBMC/skin/Aeon/720p
4. now run the patch command to implement the Multiplex Plot updates to the Viewtype_Multiplex.xml file:
patch < Viewtype_MultiplexPlot.patch
The patch command will take all the code changes needed to enable the mod which are contained in Viewtype_MultiplexPlot.xml and apply them to the latest version of Viewtype_Multiplex.xml