If I understand this correctly it will not work as you intend:

1. `username` and `password` belong to the user that you _about_ to create, not a user that already exists
2. The `couch.login` call below will thus always be unauthorized

What you need is to use the base64 decoded values for any pre-existing `_auth` config. In other words the workflow would be:

```
npm login
# 1. enter my username and password
npm adduser
# 2. enter username and password for new user
# 3. npm uses my username and password from "npm login" in the request to "npm adduser"
```