2 way fixture with no switch?

i've been using a switchable 250 watt light with pretty good results, last harvest i got a little over .5g per watt. which was double that of my previous first harvest.
well im gearing up for round 3 and i have an issue.
a friend of mine brought me up his 400 watt switchable that he isnt using, im thinking cool right? well i get it and its unlike any light i have ever seen. the story is it came from a guy that advertises in the classifies in the back of high times. a number was called and an appointment made, my friend was told to go to a national guard armory and find the building with a orange door. inside were cages full of government seized property. in one of those cages were 2 guys soldering and wiring what appear to be old street lamps converted to run as remote ballasts....so im thinking hrrrrmm....
my buddy swears that all i have to do is screw in whatever type of 400 watt bulb i want and it'll fire it, but i has no switch like my 250.
any advice?