I will skip the explanation of the crossing process. It would take too much time. Just think it was a lot of back and forth, plus some extra steps that are not at some others. But there are not a lot of options between these two countries.
If you care here
is a nice write up by john downs. A few things are different, such as they do not spray the bikes, but it is reasonably similar.
As I was approaching the border, though, a pair of KLRs, came up behind me with Aussie plates. It was Adam and Mackenzie from Tasmania. Doing the whole trip from Prudoe bay to Ushuaia. There blog is here
There was also a couple from Colorado driving their car to Panama and back on almost my same time frame so maybe I will see them again too. Sometimes it seems like a very tiny world. There was also a group of Brazilian bikers heading north song a trip in 50 days that seemed very impressive.