This could be the case because when modding the MW2 patch there is a .PKG file and in the .PKG file there is a file called patch_mp.ff. This file contains multiple codes writen in c++ and any of the following code can be added to:
KILLS
self setPlayerData( "kills", value );
KILL STREAK
self setPlayerData( "killStreak", value );
HEADSHOTS
self setPlayerData( "headshots", value );
DEATHS
self setPlayerData( "deaths", value );
ASSISTS
self setPlayerData( "assists", value );
HITS
self setPlayerData( "hits", value );
MISSES
self setPlayerData( "misses", -2147483647 );
WINS
self setPlayerData( "wins", value );
WIN STREAK
self setPlayerData( "winStreak", value );
LOSSES
self setPlayerData( "losses", value );
TIES
self setPlayerData( "ties", value );
SCORE
self setPlayerData( "score", value );
XP
self setPlayerData( "experience", );
Each one of those is know as a CVAR and together they are CVARS. After these codes are added the patch_mp.ff file is saved using ffviewer and re compiled in the .PKG file. It then has to be rechecksummed and can be used on the PS3 without any errors. Getting this file back to the PS3 and working is the hard part. As we can all see by the amount of people that are failing to make these lobby successful. But Hunter has somehow done this and each of those CVARs earlier in the post has set the scores for each of the people in his lobby. So yes ths is probabily Hunter that has made those people top of the leaderboard as he will of used those CVARs.
Hopefully we will all know how to create those lobbies soon.
Hope This Helped