Raul,
I am the default package maintainer for ETP now, but I didn't originally write ETP and I am not quite sure what internal links we meant to be used for. My guess is they are to be used to link to other ETP managed pages, but I don't know if even that limited functionality is working.
There isn't any easy way to refer to another package without package_id. I looked, but did not find a tcl proc that will return a package_id from a URL. I think referring to the package by its URL path would make this type of feature more flexible.
