This repository contains toolchains usable for crosscompiling with CMake. They are meant to be used on ArchLinux, but they can also (with some directory structure modifications) work on other systems.
Suppose you have sources which use CMake build system. Create new clean build directory, pick any toolchain and run cmake with your selected toolchain in it, e.g.:
mkdir build-win
cd build-win
cmake -DCMAKE_TOOLCHAIN_FILE=~/toolchains/archlinux/Qt4-mingw32.cmake ..
Now you can compile (and install/package) the application as usual:
make -j3
make package
make me happy
The result is application crosscompiled for given architecture and system (here it is Qt4 application for Windows).
Every toolchain file has listed dependecies, which are needed for successful crosscompilation. Packages are available either in official ArchLinux repositories, in AUR or, for more exotic architectures, in my own repository.