Not exactly what you asked for, but you could create a custom pipeline job that invokes the specimen import followed by your custom tasks(s). A Script-Based Pipeline gives you a great deal of power to orchestrate multiple pipeline tasks written in a variety of languages. You can, for example, specify a <taskref> that references a built-in task implemented in the platform, such as org.labkey.study.pipeline. SpecimenReloadJob, and then specify additional tasks that you write in Python, R, Java, etc.

Adam