This is a short overview of how to build
XCA for windows.

This is for debian hosts, cross-compiling a windows binary.

Needed packages:
  mingw cross compiler
  makensis cross tool

# apt-get install mingw32 mingw32-binutils mingw32-runtime nsis

create a new, empty directory say xca-w32
unpack xca there
Use a W32 host to execute and install the selfextracting QT4....exe

copy the installed tree to xca-w32/qt/

$ cp openssl-0.9.8X.tar.gz xca-w32/
$ tar zxf openssl-0.9.8X.tar.gz

apply openssl-cross-patch:
$ cd openssl-0.9.8X
$ patch -p1 < ../xca/misc/openssl-0.9.8-mingw32-cross.patch

compile openssl with:
$ sh ms/mingw32-cross.sh

compile xca:
$ cd xca-0.6.X
$ ./configure.w32
Edit Local.mak if needed:
 if your linux-qt is the same version as the w32 one,
 keep USE_HOSTTOOLS at "yes" otherwise set it to "no"
 and say make
$ make

Fix the missing System.dll in /usr/share/nsis/Plugins by
copying it from an NSIS windows installation.
Get the mingw runtime lib:
$ zcat /usr/share/doc/mingw32-runtime/mingwm10.dll.gz >mingwm10.dll
get the precompiled db_dump.exe from an other XCA installation
$ cp db_dump.exe xca-w32

create the setup.exe
$ make setup.exe