Canon cameras commonly communicate over USB using PTP, and sometimes MTP-related methods, but whether the PowerShot S410 exposes remote shutter control in a usable way is uncertain. A practical first step is to check gPhoto/gphoto2, since it may already support remote control for older Canon compacts.

If no documented USB control exists for this model, the simplest DIY solution is usually not USB protocol reverse-engineering but a physical trigger: either a small mechanical actuator that presses the shutter button, or an internal electrical hack that parallels the shutter button contacts. That approach is often easier to drive from an Arduino-based intervalometer.

So: the protocol is most likely PTP-based, but support for remote release on this specific camera is not guaranteed. For a reliable time-lapse build, investigate gPhoto first; if that fails, use a mechanical or shutter-button circuit trigger instead.