Not a problem. I can think of reasons why someone may want to do that.
I am not sure how much 'custom' data you can send, but there are tests that require to do manual TX/RX on chosen BLE channels. The data is not completely custom, it could be a sequence or a pattern, but it is commanded by the tester.
I see two ways for you to do it:
1) Use the HCI mode of the BLE component to send commands to the radio to do a particular TX/RX. There is a project that sets up the component in HCI mode and triggers radio to do something by receiving the HCI command over UART. This project is part of the CY8CKIT-042-BLE Pioneer Kit and you can install the example projects from www.cypress.com/CY8CKIT-042-BLE.
2) Directly configure radio registers. This is harder work (plus not always advised) but gives you more flexibility. You may ask for FCC test project by raising a technical support case from www.cypress.com/support. You may need to register on Cypress first, but it is a two minute thing.
Hope this helps.