Donagh,
The log files you have found are the only ones available on the CSS at this time. I guess you could use "cmd scheduler" to execute the show flows command at an interval you decide to grab flow data..
Something like this:
CSS11501# config t
CSS11501(config)# cmd-sched ?
Execute command
record Create a cmd schedule execution record
CSS11501(config)# cmd-sched record ?
The record name (Len: 1-16)
CSS11501(config)# cmd-sched record pete ?
The minute of the hour (0-59). Enter a single integer,
Wildcard *, comma separated list, or dash separated range
(Len: 1-40)
CSS11501(config)# cmd-sched record pete * * * * ?
The day of the week (1-7). Enter a single integer,
Wildcard *, comma separated list, or dash separated range
(Len: 1-40)
CSS11501(config)# cmd-sched record pete * * * * * ?
The command(s) to be executed (Len: 1-255)
CSS11501(config)# cmd-sched record pete * * * * * "show flows" pete.txt
Where pete.txt is the file where the output would go..The "*" are the time of data, minute, date, etc.. Just hit "?" for help as you get to each one.
Let me know if this helps
Regards
Pete..