Compilation errors

Hi, 
I want to build the InfoZip, Unzip as dlls on NT as well as on Unix. Is there a consolidated list of preprocessor variables that need to be set to see the build through. The readme file doesnt provide these descriptions clearly. I figured out some of the preprocessor variables and I think I am halfway through. But I am stuck at one place where by including USE_ZLIB definition it is expecting 'zlib.h' file to be present. This file is not a part of the distribution currently. I dont know if this is a seperate library that I need to fecth from else where. Any help would be appreciated. Thank you in advance.

Regards, 
Prakash.