Bryan,
To thank you for being a long time Amigopod customer I would like to help you out with this.
Let me ask you a few questions to scope this a bit better:
1. How many access codes do you have? A few, a few dozen, hundreds?
2. What is the time period over which you would like to run this report? i.e. How many days does the report need to cover? (It would be easier to develop the report if it only has to cover 1 day)
3. What is the typical length of sessions for guests on your network? Do you see lots of very short sessions (< 5 minutes) or do they tend to average a bit more?
4. How many sessions are you currently delivering in the course of a typical week?
5. What is the desired output of the report - would something like the following CSV work (alternatively, HTML table):
Report for date: December 6, 2012
Access Code,Max Concurrent Sessions
CODE1,10
CODE2,4
CODE3,23
6. What is the field name for your Access Code? I assume that this is being tracked with each guest account.
7. How do you want to treat MAC caching? Should a MAC cached account be included in the concurrency count or not? Are the MAC cached accounts also getting a copy of the access code? (It might not be possible to get accurate counts in the report if the MAC account does not also have the access code.)