you need to edit line 2 of the Yahoo/BOSS_include.php file:
$url = 'http://boss.yahooapis.com/ysearch/web/v1/'.urlencode($term).'?appid='.$appID.'&view=keyterms&sites='.urlencode($sites).'&abstract=long&count='.$count.'&format=xml&start='.$start;
for the 'inurl' filter:
$url = 'http://boss.yahooapis.com/ysearch/web/v1/inurl:'.urlencode($term).'?appid='.$appID.'&view=keyterms&sites='.urlencode($sites).'&abstract=long&count='.$count.'&format=xml&start='.$start;
for the 'intitle' filter:
$url = 'http://boss.yahooapis.com/ysearch/web/v1/intitle:'.urlencode($term).'?appid='.$appID.'&view=keyterms&sites='.urlencode($sites).'&abstract=long&count='.$count.'&format=xml&start='.$start;