49'er
The 49'er uses the ISDE rules. You can review the rules by going to District 36's site at
www.ama-d36.org/ . Look under "Rules". There will be supplemental rule references at that location to the AMA and FIM rules.
If you've ridden that area before, you will know that it is not a real "technical" riding area.
As far as the event goes, it consists of a route similar to an enduro except you can arrive to the checks early without penalty as long as you do not enter the check until your minute. Each check should have a indicator of the minute the check is receiving. Usually, the ride from check to check is brisk, but not race speed. Most can arrive on time or early unless trouble is encountered. Special tests are conducted during the race at various points. In the last 49'er the special tests were predominately point-to-point cross country speed tests where you are started at a control point and ride as fast as possible until you reach the end control point. Your elapsed time for the mileage, usually about 5-7 miles is recorded and compared to the best time for the test. Points are added for each second you are behind the overall leader. I believe they had five of those tests last time. You can also lose points if your bike won't start and move a certain distance at the start within one minute after your start time is called.
There may be other tests, but this is all they had last year. I'm sure others can add more detail if necessary to what I wrote. Good luck.