"Perth" is a normal unix zoneinfo file, modified for daylight saving in
2006-2009. Should work with Linux, BSD, Solaris etc. 
Mac OS X users might find http://www.csse.uwa.edu.au/~philip/wadaylight/
useful.

Copy it to /usr/share/zoneinfo/Australia/Perth (make a backup of the old),
and check that it works with
zdump -v Australia/Perth

You might also want to copy it to Australia/West. Most programs will need
restarting for the zonefile to take effect - restart daemons manually or
reboot if uptime is not so important.

The input to "zic" was:

# excerpt from FreeBSD's, requires Aus rules (or comment that line out)
# http://cvsup.pt.freebsd.org/cgi-bin/cvsweb/cvsweb.cgi/src/share/zoneinfo/australasia?rev=1.25.10.4&content-type=text/x-cvsweb-markup
#
# Western Australia
Zone Australia/Perth     7:43:24 -        LMT        1895 Dec
                         8:00        Aus        WST        1943 Jul
                         8:00        -        WST        1974 Oct lastSun 2:00s
                         8:00        1:00        WST        1975 Mar Sun>=1 2:00s
                         8:00        -        WST        1983 Oct lastSun 2:00s
                         8:00        1:00        WST        1984 Mar Sun>=1 2:00s
                         8:00        -        WST        1991 Nov 17 2:00s
                         8:00        1:00        WST        1992 Mar Sun>=1 2:00s
                         8:00        -        WST        2006 Dec 3 2:00s
                         8:00        1:00        WST        2007 Mar 25 2:00s
                         8:00        -        WST        2007 Oct 28 2:00s
                         8:00        1:00        WST        2008 Mar 30 2:00s
                         8:00        -        WST        2008 Oct 26 2:00s
                         8:00        1:00        WST        2009 Mar 29 2:00s
                         8:00        -        WST