There are several different types of page in the eprints WebsiteInterface and they are generated in different ways. See WebsiteInterface for an explanation.
Every page on eprints is wrapped in the site template. This can be found at /opt/eprints2/archives/myid/cfg/template-en.xml
Changing the Template
Make your changes. Be careful not to remove the <pin> elements as this is how eprints knows where to insert information.
Note that this file is XML so all tags must be closed correctly.
Cause the new template to be applied
TIP: If you want to see the new template in situ without waiting to update all the webpages then run "generate_abstracts myid 66" (or some other existing abstract page) and see the change on that one page.
This is slightly different for each part of the site...
run force_config_reload or resart the webserver