[Hackers] How to create a PL/iSQL package

hello, I would like to know what are the steps needed to create a PL/iSQL package in C. Correct me if I'm wrong but I have not found it the documentation ? Could you please detail how code should be organized: for example if I want to implement DBMS_LOCK with C code In IvorySQL , what would be main steps: - which files should be created or modified (including for tests). - other things to know ? Thanks and regards Pierre