Does anybody know if this is possible, I have scoured the documentation but not been able to find the AT command to do so, but have been told it is possible.
Can it be done by just reading the TX pin and writing to the RX pin?
Yes, it is…
… but not with AT commands.
That is correct - read the section on the “Flow Control Manager” (or “FCM” for short) in the ADL User Guide.
No.
Where can this be found
The documentation is included in the SDK Installation.
The precise filename depends on the particular SDK version that you have, but it does contain the words “ADL_User_Guide”
It is a PDF document.
You cam download the SDK from the developer site, or request it from your Distributor.