How to compile libxml2 and libcurl to 32-bit under 64-bit machine?

How to compile libxml2 and libcurl to 32-bit under 64-bit machine?

I download the packages libxml2-2.9.1.tar.gz and curl-7.31.0.tar.gz from
thw web. If I compile these two under 32-bit machine, it'll be ok. But
formal environment is 64-bit machine, after I compiled thest two, libxml2
and libcurl became 64-bit. When I ran the application program, it reported
an error. Now, how can I compile these two packages into 32-bit, under a
64-bit machine? I found on the 64-bit machine, there is an old package
libxml2.so.2.6.26 in /usr/local/lib, it is 64-bit file; but in /usr/lib,
there also has a file libxml2.so.2.6.16, it is 32-bit. It really confuses
me a lot.
I just hope the application program can run ok, Someone help. Thanks a lot.