i added in something similar. our logs were same as the standard format described in the docs. i didn't know / care about the last two fields, however i grouped them together for you for future reference (they could easily be whacked off). note i also used their field names, rather than apache, squid, etc.
(?P<remote_addr>[\d\.]+)\s-\s(?P<remote_user>\S+)\s\[.+\]\s+(?<request>.+\sHTTP/\d\.\d)\s(?P<status>\d+)\s(?P<bytes_sent>\d+)\s\"(?P<http_referer>[^\"]+)\"\s\"(?P<http_user_agent>[^\"]+)\"\s(\S+)\s(\S+)
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