I don't know how to do in Max, but it's really easy in Blitz. Just use the FitMesh() command, and give it the size you want, and it will scale the model to right size, no matter size it started out as. Here's an example so you know how to use it. Just make sure you replace the filenames with names of models that are on your hard drive somewhere.
Graphics3d 640,480 SetBuffer BackBuffer() Camera=CreateCamera() PositionEntity Camera,0,0,-7 ;Load in your meshes here ;------------------------ Obj1=LoadMesh("obj1.b3d") Obj2=CreateSphere("obj2.b3d") ;Now Use FitMesh to Scale them ;----------------------------- FitMesh Obj1,-1,-1,-1,2,2,2,1 FitMesh Obj2,-1,-1,-1,2,2,2,1 PositionEntity Obj1,-3,0,0 PositionEntity Obj2,3,0,0 While Not Keydown(1) Cls UpdateWorld RenderWorld Flip Wend