The IDPS (called ConsoleId on PSVita) is a 16 bytes value that contains console specific information.
How to get the IDPS of a PSVita ?
With a PSVita HEN
Install VitaCID by Major_Tom (aka tomtomdu80): [link]
Follow the instructions. A file CID.bin is created on the path: ux0:CID.bin. The IDPS of your PSVita is the 16 first bytes of CID.bin.
Install PSV IDPS Dumper by Yoti (aka RealYoti): [link]
With an ePSP CFW
The PSVita and its PSP Emulator share the same IDPS. You can grab the IDPS directly from the PSP Emulator using a PSP homebrew which reads PSP IDPS (requires an ePSP kexploit) like psp_idpsdump.
This homebrew reads IDPS from IdStorage.