This is how I compiled the PNG lib.

1) Get latest version of zlib in source code form 
   from http://www.info-zip.org/pub/infozip/zlib/

2) Extract that archive into C:\zlib

3) Use MY makefile.bor to compile each .c file 
   into an .obj file. 
   - edit makefile.bor to point to your Borland C/C++ compiler
   - run CMPZLIB.BAT to make object files

4) Run my batch file LINK.BAT to link the .obj files
   into zlib.lib.  As above, you'll have to edit LINK.BAT
   first to specify the location of your C compiler.

5) Now that you have built zlib.lib, go get the latest
   PNG lib source code from here:
   http://www.libpng.org/pub/png/

6) Use my makefile, PNGDLL.MAK, to compile each .c file 
   into an .obj file. This one will also link them together
   into a DLL.  Before doing this step, you need to edit 
   the makefile to point to your Borland C/C++ compiler.

7) That's all!

PS: I used BC++ v5.0
