Read your xml into and array, then set up a foreach loop which creates all the variables from your data and finally writes a line out to your the POI table in your Porpoise db.
mysql_query("INSERT INTO POI (
imageURL ,
linkURL ,
layerID ,
anchor_geolocation_lat ,
anchor_geolocation_lon ,
text_description ,
text_footnote ,
text_title
)
VALUES (
'$photo[url_m]', '$linkURL', '1', '$photo[latitude]' , '$photo[longitude]' , '$displaytime' , '$photo[ownername]' , '$shorttitle'
)") or die(mysql_error());