Use SoapUI classes to inspect test case XML's

I have custom Groovy classes that mine SoapUI test case XML files for various kinds of information.  I'd like to replace my custom classes with calls into the SoapUI class library.

Can I use the SoapUI class library for inspecting individual test XML files, or do I have to load an entire Project to get at individual files?

If someone can point me to relevant examples or documentation, I'd appreciate that.

Thanks!