I would make you an example but I am not in front of max ATM
The trick is to use a low res copy of your ocean mesh as your deflector. You can easily get away with enough mesh match the general shape of the surface, not all the secondary and tertiary ripples. This is obviously pretty shot dependent but you can adjust that interaction.
I learned another trick from Brandon Davis and adopted it for particle collisions, create a piece of geometry that matches the cameras frustum. There is actually a real cool script by Matrin Breidt called viewFrustum at scriptspot that does this for you. Use this geometry to delete all of the collision mesh that is outside the view of the camera, this speeds up collision calculation significantly, especially when use large complex meshes. There is no reason for pslow to try and calculate a collision surface that is nowhere near where particles are colliding.
Edit:
About the foam maps, hmmm, you could probably shape mark the surface.
I guess the point I’m getting at is you can do this fairly easily in max and that there is no plugin, that I know of at least, that does this, apart from naiad or realflow.
If I get a little time later I will build an example.