The old way to do it is to take the low quality model, the vlo, and then export that as a directX file mesh (.x)
Then you have to open it up with notepad and delete everything below meshnormals and everything above frame main.
Then load it in collmaker, which will make a col out of it.
Open it in colleditor 2 and change it to a SA version col.
Add some spheres in it so it looks like a default col.
Then export the final version using this file as the collision model.
There may be a newer, easier way though.