I’ve had this same situation in the past. I created a Java class that has nothing in it but a static Hashtable and placed it in my package code directory, then wrote some Java services to add and retrieve values from that hashtable. It’s then easy to just add the values in your XML (or properties, or whatever else) using the add service and retrieve them when necessary with the retrieve service.
And before you ask, no, I’m not allowed to post the actual code. My company doesn’t allow me to post code that I’ve written for clients.