Arduino as FTDI adapter?

I need to connect 3dr radio's air module to PC for config and I need a USB to FTDI adapter for that. I have arduino mega2560. I can't find the adapter at local stores and online would take forever to ship (I'm from Lithuania). Can I somehow use arduino to connect the module so it's recognised as a com port which can be configured using mission planner?

I thought of using Serial (usb) and Serial1 (to module); I upload a sketch which forwards data received from usb to module and vice versa; can I do that and then connect using mission planner and successfuly configure it?

See here to get started

I didn’t need to do any special sketch programming
Once the connections were right, I just set the port speed
and data to/from the FTDI port, passed through to the USB virtual comm port