[CMake] generate multiple packages the easiest way

[AKHRES Nader]

Hello,

I've looked at the archive but can't find exactly the answer suiting to 
my case.
I need to create several packages (for instance nsis AND zip) of exactly 
the same source tree (no components).
I've first try to use a list for CPACK_GENERATOR (SET(CPACK_GENERATOR 
"NSIS" "ZIP")) but it generates only the first type package (nsis here).

Is there a way to make it works?
Maybe I need to do separate cpack command and script for this?

thanks for your help