I gave this a try in max 2010 and you are correct- max will not bake an object space map without a projection modifier. You could duplicate your lowpoly model, assign that to the projection modifier, and then use a very very small cage.
I can not bake an Object Space/World Space Normal map without using a projection modifier and a (highpoly) reference (It defaults to a tangent based NM). Tangent based maps can be baked without a projection. There are two reasons why I want to generate an object space Normal map without a projection modifier: [1] Use the…