Credit Terms functionality

Hi peeps

I'm implementing my 5th OpenCart website for a new customer. They have asked for something that's totally stumped me...

Credit Terms. They want customers to be able to open a Credit Account and then place an order, all online (as opposed to having to phone up and go through a credit application).

So in essence:

New customer places order.
Signs up for account, and selects option for a Credit Account.
Submits Order without having to pay.
Credit Department credit checks the new customer and if approved, allows the order to be dispatched.

Is this possible already, or do I need a specific extension? And if so, can anyone recommend something?

Bump!

I guess this just isn't possible then... Is there really no-one with some advice on here?

Surely the cheque/money order option would work? The actual credit control (i.e checking whether the client is worthy of credit etc) is done offline anyway...

I think that's what I kinda ended up with, but thank you sincerely for taking the time to respond.