John,
1.) The LM5122 is installed in WEBENCH® with a Circuit Calculator which means you can design circuits with it. It does not have simulation enabled at this time. If it did, ther woule be the following button available:
2.) If you want to simulate the circuit, there is a TINA-TI reference design available. The PSpice model can also be used in PSpice version 15.7 or higher. The model is encrypted in both TINA-TI and PSpice. At this time, you cannot import Spice models into WEBENCH®.
3.) If you have PSpice ot TINA-TI, you could create the EVM from the EVM documentation and simulate it. You might have to import other components (FETs and diodes) as those may not be available in either tool. You could use theones in the TINA Reference Design.
Britt