The entire car goes into the Will Call lot. The Will Call person goes to the window, others can join or just stretch their legs. Once the ticket is obtained, you all pile back into the car & will head back towards the Gate line. You'll be directed back in.
Do not have someone "just get out of the car" - there's a very good chance they will get stranded, and they will not be allowed to walk into the city (which is well over a mile away)
Make sure your Will Call person has their confirmation paperwork (printed copy of the email) & their ID before you head out. If their ticket isn't at Will Call the entire vehicle will have to drive them back to Reno before heading back in. (Worst case scenario, unlikely to happen, just a warning)