Yeah, boilovers suck. I've had them using my converted keg! But, that's because I was not backing off the heat at the start of the boil.
Another thing you may or may not have tried is spraying some water into the kettle when the boilover begins. You'll have to do this a few times, but it'll keep it from going over. Of course you've got little room to play with, so it might not be as effective.
May you go marching in three-measure time
Dressed up as asses, drunk to the nines
Swing from the rafters, shouting those songs
Gone unsung for far too long