Get values from Create New / Items / Parts pop up

Hello everyone.

I have a issue and I need some help.

To create a new Item/Part, a popup is opened and I fill the mandatory fields.

I need to create a Script PX to get this values informed in the fields of the popup, in a Pre Trigger Type, to validate the informations, before saving.

My problem is how to get this values in a Pre Trigger Event.

Some idea?

I'd like to thank in advance.

Best regards.