Since the steps required for a fully manual sign-in are quite complicated and troublesome, you can automate them by using the NameID extension for Mozilla browsers. Try it out:
Alternatively, you can also install the extension from the official Mozilla add-on catalog.
When the extension is installed, you have to make sure that the
daemon is running, and check the connection settings in the extension's
preferences dialog. Those must match your
file. When everything is set up, the extension will allow you to automate
the signing procedure whenever it recognizes a login form for NameID.
It may ask for your Namecoin wallet passphrase in case you have an encrypted
and locked wallet, but appart from that, you only ever have to enter
the identity you want to use and submit.
Copyright © 2013–2016 by Daniel Kraft. NameID is free software under the terms of the AGPL v3, check out the source code!
BTC: 1Nameid3brhZrbTN1M7t6afMAfVBiGioJT | NMC: NAmeid5L2ZcaQFszYwk4sa929zbQymaaWa