lib/latest.lib.php 를 여시면
중간쯤에
$sql = " select * from $tmp_write_table where wr_is_comment = 0 order by wr_num limit 0, $rows ";
부분이 있습니다

if($bo_table=='해당게시판명')
{
$sql = " select * from $tmp_write_table where wr_is_comment = 0 and wr_1= '고양이' order by wr_num limit 0, $rows ";
}
else
{
$sql = " select * from $tmp_write_table where wr_is_comment = 0 order by wr_num limit 0, $rows ";
}
으로 처리하시면 되실듯 합니다

다른 방법
lib/latest.lib.php
$sql = " select * from $tmp_write_table where wr_is_comment = 0 order by wr_num limit 0, $rows "; ---> 수정 $options 추가
//수정 후
$sql = " select * from $tmp_write_table where wr_is_comment = 0 $options order by wr_num limit 0, $rows ";

최신글 출력시
<?=latest("basic", 'test', 10, 70, "'and wr_1='고양이'");