radius - pppoe redirect

Is there anyone who may be able to point me in the right direction in completing this task, the problem is I think I found a similiar statement at http://forum.mikrotik.com/t/redirect-http-for-pppoe-users-with-radius-attribute/29518/1 with no resolve. So I am not really sure how to do this or at this point if it can be done. Please shed some light on what needs to happen or if this isn’t possible.