Hi guys, my first post and pretty defeated

I found this example of checkbox's which filter the markers, for V3 of google api.
http://www.geocodezip.com/v3_MW_example_categories.html

Only problem is, the xml file: www.geocodezip.com/categories.xml for each marker looks like this:
<marker name="Tourist Information 6" address="10-12 York St, Blackpool, Lancashire, FY1 5AQ" lng="-3.052919" lat="53.810556" category="info"/>

In my example, I am displaying services for each location, so results will cross over, some markers will load with certain settings, it is not as black and white as this example.
this is my xml setup:

<marker>
<title>TITLE HERE</title>
<description>Great place.</description>
<address>Europe</address>
<styleUrl>#Style</styleUrl>
<lng>3.89825</lng>
<lat>52.3755</lat>
<markerid>2</markerid>
<service>planes</service>
<service>cars</service>
<service>boats</service>

</marker>

The number of <service> will vary depending on the marker.
Can anyone help please, I am really stuck with this, this appears to be the closest thing to what I am after, but the setup of the xml file means it is the wrong kind of conditional

thanks