I have a bit of a problem with overriding for the enum datatype, as I would like to override by content class attribute rather than content class. I need to do this as in the conent class that I am designing a template for there is more than one instance of the enum datatype in that class (called download_review). Is there any way to do this?
That's not possible in the template override system, you will have to do this in the template itself by looking up the attribute and probably use the switch construct:
Probably too fast and short answer: you will need to do it in the template of your new class. Create a basic template in the admin -> setup - > templates interface with a "view without children". This gives you all the attributes. Now you can copy the content from enum.tpl here and change the display as you want to.
If one attribute has influence to another, use the switch construct as hinted above.