Unfortunately, events can't look at the time to determine whether or not to trigger. However, I have a couple of thoughts.....
1. Create a process that runs every hour. On the even hours, this will create an empty file with a specific file name, on the odd hours it will delete the file. This could be scheduled from with BOE or from the Windows Scheduler.
2. In the CMC, create a file based event that looks for the existence of the file from step 1.
3. Schedule your report to run every 2 hours, based on the event from step 2.
I haven't tested this, but I think it will work.
-Dell