[CMake] path for install cmake scripts

[Weng Xuetian]

Hi folks,
I have a program that have some cmake scripts to be installed in order
to add support for find_package for this program's libs.
But I have problem about choose the cmake path.
Currently I use ${CMAKE_ROOT}/Modules to install my scripts. But this
is not good if user want to install with a custom prefix under his
home directory.
How can I get a cmake scripts path with a custom prefix?

Regards,
Xuetian