How to point cmake at specific directory for library?

I have a CMake project where I am using a library and now I want to test my code with a different version of that library. I can set INCLUDE_DIRECTORIES (and possibly later also linking) in the below example. But because I only want to do this temporarily,I'd like to manually set this path with ccmake/cmake-gui.How do I do this?

project(min_example)
cmake_minimum_required(VERSION 2.8)

find_package(OpenCV REQUIRED)
# Without the following line please:
INCLUDE_DIRECTORIES("/home/me/src/opencv/install/include")
add_executable(min_example main.cpp)

target_link_libraries(min_example ${OpenCV_LIBS})

This should be possible by setting the 

CMAKE_PREFIX_PATH

 variable upon configuring your build. In your project directory generate a 

test_build

 directory and run:

mkdir test_buildcd test_buildcmake -DCMAKE_PREFIX_PATH=/home/me/src/opencv/install ..

Setting the 

CMAKE_PREFIX_PATH

 variable will make the 

find_package(OpenCV REQUIRED)

command pick your OpenCV installation in 

/home/me/src/opencv

 and set the 

OpenCV_LIBS

 and 

OpenCV_INCLUDE_DIR

 variables accordingly.Alternatively you can edit a 

CMakeCache.txt

 file of an existing build directory with the CMake GUI editor and add the 

CMAKE_PREFIX_PATH

 definition there. You have to re-configure your project then.

1	howdo you list more than one directory on the cmake_prefix_path? – AndrewHundt Jul22 '15 at 16:58
6	@AndrewHundtset it to a CMake list, i.e.  cmake-D "CMAKE_PREFIX_PATH=/a/b/;/c/d"  – sakra Jul22 '15 at 17:05