Interfering with the GTP-u Kernel module

Hello, I would like to implement a command line tool, which will be able to open / close , read / write to gtp tunnels. I was able to install the libgtpnl library, but due to lack of documentation I have no idea where to start. Is there some sort of documentation available for this library? I need to be able to create and delete tunnels without the GTP-C communication, so just basic command line tool like create-gtp-tunnel + arguments like IPs, version and teid. The GTP-U tunnels must be kernel based. I have the latest kernel with the gtp kernel module loaded. Any help is appreciated. Thank you, Tomas