As Jeff says, Alaska & Hawaii have been moved/projected/scaled differently from the rest of the US, in this particular map (mapsgfk.us). Therefore, there is no one/simple command that will move/project/scale arbitrary lat/long coordinates and have them line up with the map.
But ... mapsgfk.uscity has applied the same move/project/scale to all the mapsgfk.uscity locations, so they line up with mapsgfk.us ... and therefore if you find the closest city to each of your lat/long locations, you could look up the x/y from mapsgfk.uscity, and plot those locations on the map. Here's a small example showing all the mapsgfk.uscity locations overlaid on mapsgfk.us:
title "mapsgfk.us with mapsgfk.uscity locations overlaid";
proc sgmap mapdata=mapsgfk.us noautolegend plotdata=mapsgfk.uscity;
choromap / mapid=statecode;
scatter x=x y=y / markerattrs=(size=1px color=red symbol=circlefilled) transparency=0;
run;
... View more
