jit.gl.imageunit

Hello :

I am not sure whether this topic was already dealt with in another thread, or in some documentation that comes with jitter - if so, please point it to me.

I am using max/msp/jitter v4.6.3 in the context of a live performance (some kind of intermedia performance which involves a large cinema screen with musicians and dancers and we call it live cinema) in an arts center near Paris in France, and I am having problems finding documentation about how to create a new effect to be used with jit.gl.imageunit.

Has anyone done it ?

I have found official Apple documentation on how to write a Image Unit (especially the kernel), and Xcode offers me a template to do so, but I have no idea what should happen next, namely how to debug and try my filter.
Shall I simply put it in the "/Library/Graphics/Image Units" directory ?
I have such a directory - and it is empty.

Where do all the existing (built-in) filters sit ? I cannot find them anywhere.
Is there any way to look at their source code (kernel code) ?
Is there any place online to look at the source code of other filters written in Core Image Kernel Language ?

thanx for your help -

michael.