[Threshold]

pawn Код:

stock Comma(numbers)
{
    new temp[24];
    valstr(temp, numbers);
    for(new i = strlen(temp) - 3; i > 0; i -= 3)
    {
        if(temp[i - 1] != '-') strins(temp, ",", i);
    }
    return temp;
}

Not that hard, is it?