make install in a custom directory
use one of the following ways
(1) make install DESTDIR="/some/absolute/path"
(2) make DESTDIR="/some/absolute/path" install
(3) DESTDIR="/some/absolute/path" make install
(4) export DESTDIR="/some/absolute/path
make install
till now i've discovered 2 ways, either changing the CMAKE_INSTALL_PREFIX or making/changing the DESTDIR env var
not sure what's the difference is
(those ways were excerpted from http://www.cmake.org/Wiki/CMake_FAQ#Does_CMake.27s_.22make_install.22_support_DESTDIR.3F )