Off the top of my head, if you are using syslog messages, you could pull a report from those specific syslog messages over a given timeframe from report writer. It would have all the information you are looking for, however, in regards to users, that would be part of the overall syslog message, so I'm not sure that there's a way to sort that way, but you could sort by the time or the device.
Regards,
Matthew Harvey