Alternate airports really are the best way. If you've already bought a ticket ex-ONT, you can read on. At the airports I've visited, there are times of day or days of week when the NoS is less likely to be used. From what I've observed, these appear to include times of reduced staffing or high passenger volume.

If you have a few hours to spare, consider arriving early as if to greet an arriving passenger and observe how the checkpoint is operating. Suppose they're using the NoS when you arrive. A half-hour later, they may turn it off. (It's TSA mini-golf! Don't hit the windmill!) Or you might notice only one lane with the NoS on. There's some risk involved here, as a BDO might question you if you appear nervous (as you likely would). But if you can act like you're just waiting for someone, then give it a shot. The checkpoint can change on a regular basis.

I've always wondered if one could bypass the NoS this way: if the checkpoint is using the WTMD when the NoS is occupied, have a colleague directly in front of you demand to try out the Super-Cool NoS and refuse the WTMD, thereby blocking the NoS for those behind! I wonder how the TSOs would handle such a situation.