My development will be done using Java.
If you want to use the TCPIP API then the source code contained in that zip will be of use to you. You will also do well to get access to the Dev Wiki which contains a lot of information on the TCPIP API too.
You may need to request access to this.
I am not using the FlexLib, but have created my own library in C# for use on Windows Phone.
There is also the objective-c source from Stu K6TU /N5AC here...
It's a case of piecing it all together - as there are no detailed manuals specific to any language.