I have just downloaded your library and i wonder i it possible to receive "HTTP POST" ??
Certainly. First, you need to configure the Arduino as a web server. The library contains code for that already.
The tricky thing is, that you need to have a look into the handling of the received html code to implement the POST command, if it is not already in. (I did not change or use the function yet, but I think one of the examples does).
When the library receives a packet, a callback function is called that handles the received data, e.g. stores it somewhere. In there, you should find the code you have to adapt.