updated boost howto

doc/boost_howto.rtf

@@ -1,4 +1,4 @@
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+{\rtf1\ansi\ansicpg1252\cocoartf1138\cocoasubrtf470
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@@ -56,6 +56,8 @@ PREREQUISITES:\
 \f1 $ sudo ./b2 install $
 \f0 , you should execute "./b2 install" instead of "sudo ./b2 install".\
 \
+- Install zlib.  This *should* be installed by default, but you might have to go get it from MacPorts (OS X) or other platform-specific package repository.  If you're not sure if it's installed, check /usr/lib, /opt/local/lib, and /usr/local/lib for libz.* (your system is not likely to have all these directories present; that's ok).\
+\
 ========\
 \
 1) Download the "Current Release" version of the Boost libraries.  At the time of this writing, this was 1.48, which could be downloaded from: \cf2 http://www.boost.org/users/download\cf0 .  Un-(zip,tar,7z) the file to a temporary location, and change directory (cd) to the resulting boost directory.\
@@ -136,6 +138,8 @@ You should see a large list scroll by, and then something like "\'85 updated X t
 \f1\i0  ;\
 		import boost ;\
 		boost.use-project ;\
+          project site-config ;\
+          lib z ;\
 \pard\tx720\tx1440\tx2160\tx2880\tx3600\tx4320\tx5040\tx5760\tx6480\tx7200\tx7920\tx8640\pardirnatural
 
 \f0 \cf0 	in a file named