Hi, not IT'y, but I believe that Paypal would be the quickest payment method to get set up. Euroconex etc. will not move that fast (vetting procedures, bond etc).
Most hosting accounts have a secure function available for shopping cart systems, he needs to check this with his host.
I believe that whoever is supplying him the product is not au-fait with the technicalities in believing that it could be set up and tested that quickly by tomorrow.
I would hope that someone will PM you through this board to offer you towards IT professional who could set up and integrate within your timeline.