Hi Vincent,
Below is the information i have regarding your query:
Lead Lifecycle status cannot be released for write access. This should always be determined by internal business logic as this could otherwise make the instance inconsistent.
However, you can use custom status in lead which you can create and map to lifecycle status. This would be available in "Business Configuration - lead finetuning activity".
Business Configuration -> Implementation Projects -> Activities -> Fine-Tune tab -> Open Lead activity -> Click on “Maintain Status” -> Add Row -> Maintain custom status (should start with “Z”) -> Map it to standard map to lifecycle status.
Regards,
Suman