Deferred payment

[mlucas]

Hello,

First, thanks to the community for virtuemart advice in this forum. 
After research on the net and on forums I have not seen similar topics.

I want my customers should pay their order when they want.
If a customer orders a product 'X' on 01/01/2013 and pay it only on 01/02/2013.

How can I do to refill the cart in an order pending status? Should I use $ _SESSION ['__vm'] ['vmcart']?

Thank you for your advice!
Sorry for my english speaking

I have Joomla 2.5.6 and Virtuemart 2.0.14

[mlucas]

no idea for anyone ? If someone have a track or a way to ...