trying to use Post-Auth-Type REJECT to insert users

Hi, The high level goal is to have a new radius server "slurp" all the users on a DSL ATM aggregation link into a SQL database. We are taking over a bunch of users from a defunct ISP and don't have the UserName / Password data. What I'm thinking is that there should be a way to have Post-Auth-Type REJECT do two SQL insert commands. Then when the user tries to auth again there will be a valid user. Will this work ?? How to have two SQL statements run when this event is triggered??? Is there a better way ?? mucho thanks.;