For now, there is only a few console emulators for the RT, the PS2 is not one of them. If you own the Surface 2 Pro then you can use the PCSX2 which is x86 compatible, but don't expect the PS2 emulator to work right in the surface 2 pro.
Keep in mind that emulating the PS2 is a very demanding task and needs powerful hardware, only PC's or laptops with decent specs can run properly the PCSX2. You won't even find a real working PS2 emulator for iOS or Android... only in PC's, laptops or some tablets with regular W8-8.1