Some time ago I wrote a plug in for MED that allows for custom primitives i.e. you can specify how many sides, radius, size, resolution, etc. of the basic plane, double sided plane, cube, sphere, cylinder, cone, and torus primitives.

I think this functionality has been added to the current MED beta so I don't know how useful this plug in would be.

If there is enough interest I can make it available for an ftp download.