Hi Jordan,
The command is still available as part of Certbot.
If you are having issues with it, you may need to try ensuring that you have upgraded to version 0.21 of Certbot. Further information is available at Solution: Client with the currently selected authenticator does not support any combination of challenges that will satisfy the CA
If you continue to have trouble, let us know where you are getting stuck with details about what command you are running and what the output is.