They're not shooting until Sunday (tomorrow) and Monday and then moving on to the 6th street bridge. Should be a tight shoot. MSwift and I checked it out last night and while security was light, it seems they've got about two blocks reserved and will be blocking it off for trailers, base camp, equipment set up, etc. that means they'd be pushing us regular people trying to see further back, not being able to see a thing.
Last night we were a block away from the tunnel and we still couldn't see much. In fact, we couldn't see anything at all INSIDE the tunnel because it was blocked by cars stacked upon cars. We went around to the other side of the tunnel and you can see through (security there too) and it seems all the action is going to take place on the opposite side. If you're planning to attend anyway, the best parking places (as trying to find parking in downtown LA is a conundrum) is a parking structure (World Trade Center) that charges $7 after 4:30 I think, or on the other side of the tunnel (with the least action) that charges $5 and you can just walk around.
Here's a wide panoramic shot I got from my angle so you guys get an idea of the location.
Left side:
Close up of tunnel entrance:
I didn't get a photo of it, but on the right side (sidewalk) they had weird props: lunch tables, shopping carts, fences, rolling chairs + more stacked upon each other.