Can the pa_project_pub API be used to add tasks to a project created in the applications form?

We have a project created with the form in Oracle Projects. Since it was created there, the pm_product_code and pm_project_reference are null. We want to add tasks to the project using the api , which is faster than keying each task in, but the API requires the pm_product_code and pm_project_reference as identifiers.

Is there a way to update the pm_product_code and pm_project_reference on an existing project so that the API can be used?

Is there an alternative way for the API to identify the project to add the tasks to?