iwmake is the tool used to generate the Qt installer binaries.

To be able to use it yourself create a config.default in the
config/ directory. You can refer to config.default.sample to see
which values need to be set within this file.

Afterwards call "iwmake.bat mingw-opensource.conf" to create an
installer package yourself.

Note that the binary creation takes a lot of time and is very
CPU-intensive as it recompiles the Qt source package among other
steps.