The current postinit message:
elog "run \"paperconf -p letter\" as root to use letter-pagesizes"
elog "or paperconf with normal user privileges."
The paperconf manpage describes -p as: "Specify the name of the paper about which informations are asked." It does not make any configuration changes of any kind.
The original postinit message recommended the use of "paperconfig -p letter", which does work to change the configuration, but somewhere along the line that got changed.
Additionally, the paperconf manpage does not suggest a way to allow a user to change their per-user default papersize. If it can do this, I recommend changing the elog message to describe how, otherwise, explain how to set the PAPERSIZE environment variable per-user.
See also Bug #186179 for a previous change to the message.
Since there has been no progress on this bug, I would like to propose a simple elog message update:
elog "Set /etc/papersize to \"letter\" to use letter-pagesizes"
This is simple and more correct than the existing message. It is true that the user can set his/her preferred size with the PAPERSIZE environment variable, but this probably is not worth mentioning in the elog message.
It may be worth considering dropping this elog message entirely, and simply including these directions in some guide to printing on gentoo, as it might not be appropriate to emit this kind of configuration info every time this package is installed. But fixing the elog message to be correct is a more conservative approach, and is better than nothing.
Indeed the message was incorrect. "paperconfig" now.