CCL:G: Ring pseudorotation

I'm trying to study a pseudorotation of a substituted pyrrolidine ring using GAUSSIAN 03. Although literature exists on the theme, I haven't come across any input example of it,so I'm trying to compute it in a way that I dislike particulary, which is to set a plane made of four atoms, and set one of the atoms off-plane, which is quite unrealistic. I would ask if anyone could kindly tell me what is your way of computing pseudorotation, and if you happen to have an 'automagic' way of doing so, if you would be so kind as to share it.