I will try to help you. No One has attempted it yet, so I will give you my own thoughts about it, since you seem to want help pretty bad. I will give you some comments.
First, this deep scratch, is it wide? Because if it is not, then I am wondering how you are going to be so careful as to put this clear coat gel in the crack? Also, not getting it on the surrounding paint will be a challenge. How big is the scratch? If it is like a foot. I would say you can not get good results with a brush and clear coat gel. If it is small you might want to try it, but I doubt it will turn out good. Also, the gel that you put in the cut might not BLEND so well with the original clear coat. I don't think you can take away the "line" by filling it in. Even if you were able to fill the scratch in I believe the lines would still appear.
I just saw you wanted some input or comments so there is my two cents. I think if it is big then get it done by a body shop. If it is very small try it, or try it on an area that is not noticable first. I am sure it can be done, someway, just not sure how a body shop or pro would go about doing it. I say if it is small just leave it or go to a body shop if you are very concerned.
I hope this helped a lil.
:up