Compiling boost with zlib

I did manage to build them using the option
-sZLIB_SOURCE="C:\zlib-1.2.5"
Note there is no space after the -s and the quotes around the path.

It took me a while to get Boost to build correctly with zlib support.

The problem I ran into was that at some point zlib no longer included a gzio.c source file. The jamfile for the Boost build system (jamfile.v2) had a reference to the gzio module which caused it fail. The solution was to remove that reference before building.

I'm not sure this answer is relevant any longer, unless you're trying to build an old version of Boost. I believe the original build issue has been fixed in more recent versions of Boost.