QuaZIP installation help

[skammers]

I use Qt 5.3.0 and are trying to use quazip.

I followed this instroction document: http://quazip.sourceforge.net/
I have downloaded the Qt 4 as well, so I can us the qmake 4, which is required. Also downloaded the quazip file and the zlib archive (http://zlib.net/).

I tried this:

_$ cd /wherever/quazip/source/is/quazip-x.y.z/quazip
$ qmake [PREFIX=where-to-install]
$ make
_
and I think it worked (How do I know for sure?).

Then I tried :
$ qmake LIBS+=-L/usr/local/zlib/lib INCLUDEPATH+=/usr/local/zlib/include

but got these errors:
WARNING: <internal>:1: Unescaped backslashes are deprecated.
WARNING: <internal>:1: Unescaped backslashes are deprecated.
WARNING: <internal>:1: Unescaped backslashes are deprecated.

Could someone please help me step by step installing quazip and get it to work as making a zip file is an important part of my project?