I was able to contact my friend, and he described the exercise he uses:
Sitting at the table with your elbow in a unmoving position, grasp a light weight in your hand (one-two lbs.), and flex your arm slowly up and down, to about a ninety degree bend. Do this with both your hand facing down, and also facing up, holding the weight, alternating reps. Do it as many times as still feels comfortable, without straining, building up reps over time. Don't go heavy on the weight. Support your elbow on a towel or something, if your elbow directly on the table is uncomfortable, but keep your elbow from moving around.
The important thing is to start doing the exercises only after the pain has gone away. The muscles supporting the tendon will get stronger, and help prevent the injury repeating. It's not an overnight thing, you should keep working at it. That's his advice, and apparently it worked for him.
I also read on the web where exercise to strengthen is recommended.
Hope it may help.