Using a mesh to cut through a box

[should_be_shot]

Hello,

I have a model of the statue of liberty which I have modeled a staircase in leading to a floor plane/box.  My floor is box shaped therefore sticks out of the model.  What I'm trying to do is use the outside mesh to cut a hole in the floor plane/box like a cookie cutter, so the floor plane sits nicely inside the model with no visible geometry from the outside.  I've included a picture for reference.

I've had a go with boolean but I'm just don't seem to be hitting the right combination of options for my desired effect.
Any suggestions of methods or even other tools would be greatly appreciated.

Look forward to hearing from you. 

[joojaa]

is the model importerd? Have you renumbered the vertices to mayas liking?

[should_be_shot]

Cheers for the reply 

The object was downloaded and imported into 3dsmax the file was originally a max file.  I'm not sure what you mean by renumbering the vertices, Does this still apply to 3Ds max?

[joojaa]

Ahh sorry forum blindness (max and maya 2011 look astonioshinly similar). Yes max has same kind of problems but if you got the file as max then you will have no idea whet it came from. Assuming your normals point the right way your boolean shoule be set to interesect.