Ya, but you might get troubles such as heat and the light being too intensed. I tried with one and it worked, but I lost a lot due to previous errors. I think you should get some fluorescents first, but if you do decide to use that 400MH lamp. Keep it far away...make some kind of dome for the seedlings to hold moisture...and the biggest problem I had was over watering/ under watering.
Oh and be careful, that MH will increase the temperature hella!