The tests must be automated, or you won't get your XP merit badges. However, there are lots of ways this can be done. The specific choice is up to your programmers. Here are some starting ideas:
If the program is a batch program, reading inputs and producing outputs, make a standard series of input files, run the program, check the output manually (and carefully) once, and then write simple scripts that compare the test output to the known good output.
Use the above trick for reports and lists from any program, batch or not.
Build on the xUnit testing framework. Write functional tests as programs. Better yet, make a little scripting language that the programmers can use. Then grow it and make it easier until the customers can ...