You'll have to create your own custom log format, as the one's awstats ship with are all the common webserver formats, and we store data in a propietary format i.e. objSiteLogs.AddSiteLog(PortalSettings.PortalId, objUserInfo.UserID, URLReferrer, Request.Url.ToString(), Request.UserAgent, Request.UserHostAddress, Request.UserHostName, PortalSettings.ActiveTab.TabID, AffiliateId, intSiteLogBuffer, strSiteLogStorage) [note:this doesn't support optional changes) . Theres some notes in the awstats.conf file, and @
http://awstats.sourceforge.net/docs/awstats_faq.html#LOGFORMAT on how to create custom logfile formats.
Realistically, if you're using awstats, you're probably better pointing it at the raw IIS logs.
Cathal