You can't. Always check to see if your applications are compatible with the newer version of OS X that you're installing. Office 2004 is PPC application and can not be run in Lion or Mountain Lion which can only run Intel apps. You need to find someone who has a Mac and is still running Snow Leopard or below in order to access your Entourage 2004 mail and documents.
I don't believe that will work because even if you had a later version of Office with Entourage (Office 2008) the identities would not be compatible from one version to the next. The data base entries themselves could be transferred though. Find a copy of Office 2008 on ebay and give it a try. Office 2008 will work with Mountain Lion.
Both Office 2008 and 2011 can exist on the same machine. However, the documents and templates along with the main identity will be shared. I had them both running on my machine but later decided to remove Office 2008 and only work with 2011. You'll need to be very careful removing 2008 if you have it installed along with 2011 because you may remove something that 2011 needs.
The Microsoft Mac Office web site provides instructions on how to completely remove 2008. I find it best to follow their instructions rather than using the 2008 uninstaller. Here is the LINK.
Yeah, you're going to have to manually remove Office 2004. Don't get too worried about it though.... just drag the Office 2004 applications folder to the Trash and empty it. Don't attempt to remove the preference files or anything else for fear of messing up Office 2008. What it leaves behind are small files that don't amount to very much space.
thanks. i bought office 2008 from ebay and have been able to get entourage 2008 to work with mountain lion.