[CMake] Getting cmake to apply patches

[Hugh Sorby]

So I am trying to get CMake to apply patches to third party source. 

First off can someone confirm (, I'm hoping I haven't missed the 
obvoius) that there isn't an inbuilt command to apply unified diffs.

Secondly can anyone tell me how to stop CMake consuming the "-i" in 
following command:

cmake -E netgen patch -p0 -i netgen-4.9.11.patch

At the moment I am trying to achieve this on Windows Vista.
Ta.