Create new user account

[BulliM]

I try to add new users by an own php script. Is there a vb method, to create new user accounts to vbulletin without using admincp ?

I have USERNAME, EMAILADRESS, PASSWORD and other defaults if needed.

Todo:

1. Have to check, if username already exists.
2. Convert password into token and secret. (May a function do automatically?)
3. Write new user into database.

Two questions:

1. What is the easiest way to do this?
2. Are there any steps to do furthermore?