The first time is where all the work is. The key to "how many" people is not many for the first assembly. Few people really know how to assemble things correctly these days. Even fewer want to take the time to do it right. I spent the better part of two weekends assembling mine by myself and assisted on the second weekend by only my brother who is a machinest by trade and more of a perfectionist than me. We followed this guide to get smooth transitions between the lanes.
http://waynesthisandthat.com/how%20to%2 ... track.html
You will need to adjust lanes as he describes by bending at times. We did blend the lanes with 600 grit, then 1000, then 000 steel wool and then a final polish of the track. It ran beautifully from getting the initial assembly right. The nice ting is you can do the section to section assembly one at a time at home if needed in limited space.