It looks like you need an external CMake project. I worked with him quite extensively in developing the Titan build system and provides a way to manage several of the original builds. You can enable ExternalProject, and then something like the following will build the project:
ExternalProject_Add (Qt
DOWNLOAD_DIR $ {CMAKE_CURRENT_BINARY_DIR}
URL $ {qt_file}
UPDATE_COMMAND ""
SOURCE_DIR $ {qt_source}
BUILD_IN_SOURCE 1
CONFIGURE_COMMAND $ {qt_configure}
BUILD_COMMAND $ {qt_build}
INSTALL_COMMAND "$ {qt_install}"
)2009 . , make, -, Qt, configure Windows, Mac Linux.