SetScore
From the Scripting Manual
procedure SetScore(ID: byte; Score: integer); Parameter Info: ID (Byte): Player ID who will have their score (Kills) modified. Score (Integer): New player's score. Description: This function will set the players score (kills) to a new value.
Examples
begin
SetScore(1,GetPlayerStat(1,'KILLS')+10); // This will add 10 points to player 1's current score
end;