We could probably get DLP to report/trigger on these devices but I honestly don't see any good coming from this scenario. They should be detected as human interface devices (HID) - DLP whitelists those to avoid issues with preventing users from being able to interact with the system etc. What are you trying to accomplish with having DLP track these ps/2 devices?
I was trying to get an asset list of ps/2 mice and keyboards. Anyway, I have blocked usb keyboards and mice except customer's vid/pid list. And, I have excluded all the ps/2 mice and keyboards.