change blackberry app from free to try to buy

We have an app that is currently for sale in blackberry app world for free. We need it to be changed and reuploaded to the store so that it can support "Try Before you Buy" which is basically a free trial version. Coder should have experience with blackberry apps and with app world. We'd very much like to make our app a paid subscription app. APP is done, we just need the certificates changed and keys generated as per blackberry specs to sell as try to buy. Please let me know if you can do this project.