We've wired plenty of them up before. Just make sure the light you're speaking of accepts DC not AC, most lights are built to take Dynamo power although there are an increasing number of e-bike specific lights coming available.
Overall I'm lead to believe based on the B&M website that you might have some trouble with that light, as it's really made to accept a charger, which operates very differently than this standard 6v lead.
I would recommend the B&M Lumotec Fly E, it's made for ebikes and works quite well. Let me know if I can assist further, or if you need any lights, we have several styles and are constantly getting more.