the parameters you need to adjust are more likely the ones in the IMAGE SAMPLER (ANTIALIASING) rollout wich manages the sampling geometry details, texture details and stuff like that.
this is quite different from global DMC sampler wich is more involved in manging the sampling of blurry reflections/refractions and stuff like that..
actually i think you need some basic concept about sampling, antialiasing and more..
try to google for this.. there is a lot of stuff online.. like this example links..
you may also want to read the fantastic manual on the chaos group website?
It would definitely be possible. You would have to create an "x-ray" style equivalent material in V-Ray and apply it to the component you are trying to highlight to have the effect your looking for. Try the material I've created and attached. Its going to render a bit more slowly, but it should work for what you are trying.
I maybe wasn't clear enough but I would like to use X-Ray one everything except the componen I want to highlight so that it's easier to see. It would be a lot of work if I would have to change all other material in the model to be X-Ray.
So you would need to apply this "xray style" material to everything but the object you would want rendered.