How to refer relative paths for code outside pom project?

I have a very different situation to deal with. Something never seen before.

I have a codebase which is not a maven based project. It basically is set of Pig Script that are executed on Hadoop Cluster.

Now there is requirement to test these scripts using PigUnit, so I created a maven based project with all dependencies needed for the project.

Visually it looks like

user_mapper/
           src/main/
                   user.pig
                   other.pig
           test/
               pom.xml
               src/java/
                      /UserTest.java
                      /OtherTest.java

As you could see, test is a maven based project in itself.

What I need

In UserTest.java I want to refer to relative path of user.pig

How can I provide a relative path in UserTest.java?