The LA Times has the details on how it will be set up:
At each mile along the race route — which stretches from Dodger Stadium to Santa Monica — a cluster of spotlights will shine columns of light into the sky from about 8:40 to 10:15 p.m., according to a spokeswoman from Asics, the marathon’s main sponsor.
The light installation includes 124 spotlights totaling more than 7.5 million lumens, which is equal to more than 29,000 light bulbs, the spokeswoman said. A team of about 85 people will install the lights across the city beginning Thursday.
The spectacle should make for some pretty great conditions for taking photos, so if you are into that kind of thing – you may want to make plans to head west. As for me, I will just stay here and live vicariously through your Instagrams.