Thank you for your response.
My problem is not in configuring UART module, but understand if and how I can use KW01 as a modem. I wouldn't change prebuilt firmware, but I'd want to select radio parameters using UART messages, as done with Radio Utility GUI.
Reading source code (PacketHandler.c and RadioUtility.c) I've found a simple "switch case" construct, filtering the first byte of UART message, that selects the right parameter to change. I'll follow this way to realize my application.
If I have further problems, I'll write it here.
Thank you