I don't think there is a way to put power steering on value model sportsman, the XP's are the only ones that the EPS unit will bolt into and work with the electronics the XP has. Nothing aftermarket as far as I know.
Mine- 2011 Sportsman X2 550 With EPS!!-Mile Marker 2500lb Winch, Guru Brush Guard, 3000K HID's, PIAA Driving Lights, Autometer Phantom Oil Temperature, Coolant Temperature, and Voltmeter Gauges, Polaris Low Lock and Ride windshield, Acerbis Handguards, Symtec Heated Grips and Thumb warmer, 2+2 gallon Rotopax Fuel packs, Warn 60" Provantage Plow w/ Power Pivot
Hers- 2012 Sportsman 550XP EPS Blue Fire LE 27" ITP Mudlites on ITP SS212 Wheels, Polaris 2500 lb winch
Just Because- 2000 Magnum 325 2x4