Is possible to remove this superficial scratch from my m18x r2 lid?

Those products you mentioned are for solid fill paint surfaces, your M18xR2 has an anodized surface. Anodizing, like electroplating is "grown" on to the material so it is very hard to repair once marked.

If it doesn't work you can try a professional anodizing service, but I don't like your chances.

I have this accidental scratch in my m18x r2 lid: http://postimg.org/image/db3b0fxhd/   Is possible to remove this with this product?'' Meguiars ScratchX Scratch Remover 2.0'' or ''Fix It Pro''

If those options do not minimize the damage to the point that you are happy with it, consider purchasing a replacement panel from Parts People. The M18xR1/R2 use the same part (fully interchangeable).

Black - Alienware M18x 18.4" LCD Lid Back Cover Panel - 122RP - Grade A

I have purchased numerous items from this vendor and they are excellent. 

If you are not wanting to spend $49.95 for this part, consider getting an automotive racing stripe kit from a place like Wal-Mart or AutoZone. I used a black racing stripe on my custom painted chassis, but white would look good on black. I saw it on sale at Wal-Mart not long ago for like $10. Then you would have a unique look. Cutting out the area around the alien head emblem will require some precision work with something like an X-acto knife. If you decide you don't like it or it does not turn out to your satisfaction, you can always grab a replacement lid later on.

Example:

Thanks and nice photo, my scratch is almost imperceptible and superficial i am looking for some anodized aluminum polish product like this: FLITZ METAL POLISH

http://www.ebay.com/itm/FLITZ-METAL-POLISH-LIQUID-3-4-OZ-100ml-/220791855062?pt=LH_DefaultDomain_0&hash=item33683857d6

 

but i am afraid to test :D

Parts people are a good company as BJ mentioned before, I've also purchased thousands of dollars worth of parts with no issues.

Good suggestions about the stripes, I forgot about BJ Fox's GT version :)