How to Prevent Rusting From a Deep Scratch?

[HighFlowDiesel]

So long story short, a coworker set a tool on the hood of my '95 Pathfinder (I still don't know WHY they did this...) and it ended up leaving a small, but deep scratch that goes into the bare metal underneath. As soon as i noticed it, i put some car wax and silicone grease over the top to try and keep the air out until I had the opportunity to fix it properly. Two weeks of procrastination later I come back to find it's already started to rust a bit at the corners. Now that the rust is there the only solution I know of is to sand/grind it off and paint over. AFAIK the only way I can get colour-matched paint is to have a body shop mix a can for me custom, but with how much that would cost I might as well get the whole car repainted. This seems overkill for both the car AND my wallet, since the rest of the paint is pretty much perfect. Does anyone know of any ways to get rust off without grinding off paint in the process? I don't care about making the scratch looking any better than it does now, I just want to avoid having to get my hood refabricated in 5 years because I didn't bother to get the rust off.

TL;DR, does anyone know how to get rust off without grinding/sanding it off?

(A note about the image, all of the discolouration around the scratch is the silicone grease, all the paint around the scratch itself is fine)

Thanks!

[JayArras]

Whenever I've had this issue, I use rubbing compound to remove any rust and to smoothe paint raises and then mask and lightly spray the area with a kit from places like automotivetouchup.com following their instructions. Then buff the hell out of the area with a high quality wax.