Solution can be as simple as grounding IN+ and taking Ri=3·Rf to turn -10V into +3.3V, yes. Use a single supply opamp like LM358, give it 5V power and it will be happy.
The solution that requires a precise positive voltage is to put two resistors from, say, +5V to the -10V rail in, say, 1:5 proportions, so that you get +2.5V when the rail is exactly -10V. No opamp necessary.