[Boofo]

In private.php, find:

$message[message]=pmcodeparse($message[message],0,$allowsmilies);
$message[message] .= '<br>'.$message['attachment'] . $fromuserinfo[signature];

REPLACE it with:

if ($fromuserinfo[usergroupid]==6 OR $fromuserinfo[usergroupid]==5) {
$message[message]=pmcodeparse($message[message],1,1,1,1);
} else {
$message[message]=pmcodeparse($message[message],0,$allowsmilies);
}
$message[message] .= '<br>'.$message['attachment'] . $fromuserinfo[signature];

Try that and let me know if it works for you. I haven't tested it.