Just keep it simple djcslice. For your first refoam I would avoid complex test tones, or any other outside electronic signals. For one thing it will allow you to devolop a feel between you and the speaker and thats what you want to develop right now. Outside stimuli will only insulate you from what you are doing. One other thing shims and electronic media are not 100% gauranteed, but I have never know one to fail by using feel alone as long you are constantly checking your work along the way. The shimless method also takes into account any small imperfections the various parts may have developed over time and allows you to compensate using the best tools at your disposal....your fingers and your brain. Shims and stimuli force the VC to center, but once you remove that crutch who knows.
You will be quite surprised how easy it wiil go once you get started. It's just getting past that first apprahensive step. Once you do that you'll be fine. Once you become more proficent you can begin to experiment with other more elaborate and complex procedures.