Develop additional Zencart Free Shipping Option module

We have a website running Zencart 1.5. We have used "Free Shipping Option" module to provide customers of free shipping solution if their order quantity is over certain amount (configurable). However, this module can only be used for 1 shipping zone, for example, UK. But we have 6 other shipping zones which we also want to offer same kind of free shipping options. This project requires the creation of 6 "free shipping option" modules. Each module is the same with the existing "free shipping option" module (i.e. fields, and configurability). We can then configure each one for a shipping zone. Initially we might only use 4 zones. These 6 additional modules need to be installed, and properly working. We also need installation guide once the work is completed.