I followed the setup instructions for firefox, but I got still errors about the extension not being from a trusted source.
It appears to work after I restarted firefox.
Should this step be added to the wiki?
Are you saying that you had to restart after changing the signature enforcement preference? I think the preference change should apply immediately.
That was my experience then. Not its no longer an issue, sort of.
Today it is different, first the firefox-dev command was missing from my computer so I downloaded a new copy.
With a fresh environment I repeated the steps and this time it worked without a restart.
Although my extension is running, about:addons stil says in bold red letters
…could not be verified for use in Nightly and has been disabled.
I could have been tricked by that message believing the extension was still blocked.
Update: Upon reloading about:addons the message is no longer red but the yellow one
…could not be verified for use in Nightly. Proceed with caution.
Which is what would be expected.