Radar map modification for Postals

Hello, all. I currently play on a RP server who provide me a map with postals on it. Nice. I am looking into basically putting that map file on the radar on my HUD instead of the traditional black and white with streets and sea, etc. The one way I can see doing this right now is manually going into the /x64e.rpf/levels/gta5/minimap.rpf/ and basically painting over the files with my map; But this seems like a very long and painful process.

Any suggestions?