apache & webalizer : perfect config?

At the moment I have apache and weblizer configured to produce stats from a local host every 30 minutes.

The log file is currently in Common format ("%h %l %u %t \"%r\" %>s %b") but I would like to change this to an extended format ("%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\"" ).

is there a way i can do this so that the seemlessly without having to start the stats from afresh? I suspect that I can do this by configuring the history in webalizer and rolling the apache log formats.

Can anyone help?

is what I am trying to do at all possible?

Yes, this is possible. You were asking for the "perfect config" of apache and webalizer - there is none, so this is probably why noone here gave any answer yet

- it does support CLF (common log format) and several variations of apache´s combined log format.
- it does even support proxy and ftp logs (squid / wu-ftpd compatible)
- you can make apache switch over to a new logfile in the new format and have webalizer analyze the old logfiles in the old format, tell it to run in incremental mode ("history") and then run it again on your new logfile(s) with a new configuration in regular intervals.

I successfully switched that way from CLF to one that also contains the HTTP_REFERER some weeks ago, webalizer does even show statistics for the referrers now

Webalizer is a great piece of free software. You can read about all it´s features on the webalizer homepage