toggling LFRX gpio pins

Hi guys again,

I have designed small RF frontend using TI's cc1000 transciever. Since the
transciever need to be configured using external pins, I need to be able to
toggle gpio pins on my LFRX. I have found that I should use dboard_iface
which is available in python via swig. However I have several questions:
How should I address my board, since there are 4 possible slots, and onlt 2
values of type unit, UNIT_RX and UNIT_TX.
As far as i can see, every uhd source has method get_iface, does this
anyhow concerns me?

Thanks again,
Nemanja