unicenta opos point of sale software changes - repost

Im looking to use the unicenta open source point of sale software for my business, it already has a feature/module where by customers can be added to the database as customers with a credit account. What i would like is to be able to add these customers to the database when they bring an item to be repaired, we need to record all of their details, for example - name, telephone number, address and any other fields that are required. Then i need the epos to print off 2 receipts/tickets with a receipt number, one for the customer and one for us to stay with the item. I need to be able to edit all of the fields in the entry and save when required and if the customer makes a deposit or part payment it needs to be deducted from the final balance and print a receipt/ticket when necessary. I would also like this to modified with the installer, so after you have done the work you can send me the installer and i can install it as many times as required if i have any problems with it. The software currently installs with apache derby or can be installed using MySQL, i want to use it with MySQL As the software is already created, i think this is mainly to just make changes to existing parts of the software If there is anything you are unsure please ask me.