Mark,
This alert is pulling from sys.dm_xe_session_targets looking for when a deadlock happens but, is not saving the XML anywhere and there isn't a way to attach a file to the alert emails so I don't think that this is possible in DPA currently. Please add this idea as a feature request Database Performance Analyzer Feature Requests.
There is a chart made on any custom metric when you create them. To create the metric, click on Options > Custom Resource Metrics. The charts for these can be customized by editing some XML. This gets technical enough that it might be best to explain in a support request.