The plugin function create_is_password() has been made “pluggable”.
This means that you can write your own password generator logic and save it in the file infusion4wppluggable.php, giving your function the name create_is_password(). Your function’s code will then override the built-in code.
For other pluggable functions, please see: http://releases.infusionwp.com/v3-1-43/