Depending on how bad this is it may be recoverable by either a good gun polishing using a good cutting compound such as farecla no 3. (Not the JML stuff)
Alternatly try Quixx scratch remover, it is the only 1 I have found that seems to "repair" the laquer coat to some extent. Either way be careful not to cut into the colour coat or a respray is your only recourse, this can usually be done as a smart repair rather than a full panel/panels spray job. (my day job) : )
Touch in paints, particularily on a meter long scratch is almost impossible to do efectively and often looks worse than an untreated scratch.