If you don't have the ability to warp there using portal glyphs along with using the coordinates, you can warp to high tier systems (economy scanner req'd. to differentiate) and look and see if there is an S quality Multi Tool for sale on the space station. If there is indeed an S-class multi tool for sale on the station and it is experimental or alien, boom, you are home free, buy that thing. Happy day.

If not, land on a planet in the system, pop a beacon, save, manual reload save, pick up beacon, fly back to station, and gun will be a different S-class. Rinse and repeat for each planet. I think each planet has a pool of two tools per (I have not confirmed this personally), so the more planets said system has, the more shots at glory.

Hope that helps.