Delay login until 'checkout' is selected

I'm attempting to figure out how to configure the shopping mechanism to not ask for a login/registration until the user selects 'Proceed to checkout.' Once they do select the Checkout option, then i would wish them to login or register (unless already logged into the system) and proceed from there. I am not sure where to do this.

I thought it was in the workflow in the configuration but that doesn't seem to work. Or did I miss something?

thanks,
Kurt

Solved it.