Asterisk extension xfer based on number entered

I require a custom script for elastix/asterisk. I will be adding a section on my IVR that will prompt callers to enter in a 5 digit account number. Depending on what number is entered, they will be transferred to an extension that is assigned to that account number. There will be about 5-10 different extensions and 200 account numbers. The account numbers will increase by ~50 a week. If you bid, please explain how you would go about doing this and how i would be able to add additional account numbers and assign them to an extension each week.