There are 2 new binaries that are needed to build the install ws on windows-i586. These 2 tools are provided by the Windows Platform SDK (Windows Installer SDK Feature). We need to document these instructions in the build docs. The Platform SDK can be downloaded from:

http://www.microsoft.com/downloads/details.aspx?FamilyId=A55B6B43-E24F-4EA3-A93E-40C0EC4F68E5&displaylang=en

The bundle to download is called: PSDK-x86.exe

Launch the .exe, and choose the "Custom Setup" type of install. During the "Custom Installation" dialog, unselect all Features except for "Microsoft Windows Installer SDK".