Did it!
Not the best way, it's dirty but, it works.
The following code will add all comments from all listings made on a user. Fits nicely under the user's details on the user-public-profile.php page.
<?php
$con = mysql_connect("localhost","your_db_username","your_db_password");
if (!$con)
{
die('Could not connect: ' . mysql_error());
}
mysql_select_db("your_db_database", $con);
$userid = osc_user_id();
$result = mysql_query("SELECT oc_t_item.fk_i_user_id, oc_t_item_comment.dt_pub_date, s_title, s_author_name, s_body FROM oc_t_item JOIN oc_t_item_comment ON oc_t_item_comment.fk_i_item_id = oc_t_item.pk_i_id WHERE oc_t_item.fk_i_user_id = $userid AND oc_t_item_comment.b_enabled = 1 AND oc_t_item_comment.b_active = 1");
while($row = mysql_fetch_array($result))
{
echo "<span style=\"font-size:18px; color:#333;\">".$row['s_title']."</span> <span style=\"font-style:italic; font-size:12px; color:#666;\">by ".$row['s_author_name']."</span>";
echo "<br /><span style=\"font-style:italic; font-size:12px; color:#666;\">";
echo $row['s_body'];
echo "</span><br /><br />";
echo "<br />";
echo "<div style=\"border-bottom: 1px solid rgb(221, 221, 221);\"></div>";
echo "<br />";
}
mysql_close($con);
?>