I wrote a script that adds invoice data to time records in a mass update. I need to make it a user event script that calls a custom module. My question is, if time records are added to an invoice, will that satisfy the "on create or update" criteria at the invoice level, which would call the script after submit? I'm not sure how to send the invoice to the entry point.

I have yet to do a mass update, but as long as mass updates can run userevent scripts, it should trigger it when it calls onSave

Sorry, I think you're looking at it backwards. I want the user event to cause updates to time records. So the script would change one record at a time. The way I wrote it originally, it arbitrarily updated all invoices.