If your talking about manually code processing a file to make it zipped that's a lot of work and you can find out how to do it by reading up technical papers on gamedev.net.
However Winzip has a command line version which you can make ExecFile calls with, I dont know if it's legally permissable to include it in a download but hey - using one of the wrappers above could hide it! lol
http://www.winzip.com/prodpagecl.htm?wzhcli
However Winzip has a command line version which you can make ExecFile calls with, I dont know if it's legally permissable to include it in a download but hey - using one of the wrappers above could hide it! lol
http://www.winzip.com/prodpagecl.htm?wzhcli