The LA News choppers don't really have alot of 2-way radio traffic during pursuits.
Here in Los Angeles, most pursuits that take place on the freeways are handled by the California Highway Patrol (CHP).
Here's what i would suggest:
1. Subscribe to a few twitter feeds to get alerts about pursuits. Some good ones are: @LACoScan, @ChaseAlert. They will often times mention the pursuing agency.
2. Get familiar with the existing Broadcastify streams covering LA County so you can pull up the feed quickly. Sometimes these end as fast as they start. CHP will often use the Blue channels during pursuits.
3. Search the various TV News station's web sites - Many of them have a live feed of the pursuits.
ABC7.Com, KCAL 9 News, KCBS 2 News, KNBC, KTLA will get you started.
Good Luck !
- KG6DOQ