I implemented my own OpenID provider because I wanted to control my OpenID identity myself, but ok, I look up Webfinger to see how that works.
There is a long and vague description, that I skim, which seems to explain that Webfinger is a way to translate a Webfinger ID, which looks like an email-address, to an OpenID URL, which apparantly looks very scary.
So I create the required
/.well.know/host-meta URL and configure my webserver to serve it with the correct Content-Type.
The new identi.ca fetches the file, but complains that "
Error: koldfront.dk does not implement registration_endpoint".
Searching for that seems to indicate that this is an OAuth thing, and it seems that pump.io doesn't support OpenID. I am not sure about this, because in no place is it stated or mentioned clearly. (Update: I found this: pump.io issue #534.)
Oh well, I will log in with my password then (I haven't quite got the patience to find out what is needed to implement an OAuth provider today).
identi.ca's login page explains that all passwords were reset during the conversion, so I must to go through password recovery; so I enter my Nickname and click "Recover". The reply from identi.ca? "This user account has no email address."
Oh, what genius - stop supporting the login method I have used for years, and remove the password from my account, making me recover the account via email, without checking first that you actually have my email-address on record!
This user experience is slightly flawed, I have to say.