Modify Cartweaver 4 CFM or PHP

Modify new Cartweaver 4 installation (ColdFusion or PHP version) to allow for a 5 tier option of quantity pricing not based on a simple calculated percentage discount. This discount display would come from the database where quantity pricing options are listed. Also need the mod to be editable in the admin screen Also modify CartWeaver to allow customers to insert their own UPS or FedEx shipper number in the shipping options field and not charge them any shipping as they are using their own negotiated rate with the carrier. In our current cart, when in the final shipping checkout, if the software detects any characters in the "Enter you Shipper Number", it adds this shipper number to the pick slip we receive by email and doesn't charge the customer anything for shipping. This is very common for our customers to use in our industry. Bidder must have experience with CartWeaver.