MKV Blu-ray 16:9 to 2.35:1

Hi Guys, can anyone help me in converting 16:9 MKV Blu-ray rips to 2.35:1? The reason i want to try this is i have a scope projector screen and rather than having to zoom down and have the black bars at the sides i want to try this.

Here is what i would like to do as an example: http://forum.blu-ray.com/showthread.php?t=204946

Thanks for any help.