Looks like you have to do the Sling Orange + Sports Extra package. Right now it's a free 3-day trial for new customers or $46/mo.

for people with existing accounts, active or not (such as myself).
Stream this season's top NCAA & college football games live, online, or on your favorite device with Sling TV. Watch now with ESPN, ESPN2, and others. Get started today.
www.sling.com
There are many cable and satellite providers that carry it as well. You can check on that here:
https://pac-12.com/getpac-12networks
There may be other ways, but I don't know them yet.