* 2014.08.02 update *
If you need a python code right away, then please keep in touch with https://github.com/carpedm20/LINE
Now, I decide to analyze the LINE protocol in more detail.
4. HTTP(S) Analysis
There are two particular headers, one is 'X-Line-Application' and the other is 'X-Line-Access'.
The first header, 'X-Line-Application', specify the kind of mobile phone, which is not that interesting one ;(
However, the second header 'X-Line-Access' seems like a session key and part of the key is encrypted by Base64.
I'll talk about this later :)
Anyway, after I decode the encrypted data, I can get 'iat: 1378973334524' (string data) and '��" [���<Z� � 5wxwO�' (byte data)
The format of POST data seems like 'bson' string which is used in LOCO protocol but it isn't.
As you can see in this picture, there is a string "sendMessage" which also can be found in the POST data.
Therefore, I guess that this sendMessage function makes the POST data.
I also figure out that WriteMessageBegin() and WriteMessageEnd() are the functions for Thrift platform.
I keep read some posts and decompiled codes to find out how Thrift works, but I can't figure out the exact structure of Thrift HTTP protocol.
The bellow picture is the structure of Thrift packet based on the packet analysis that I took. (which may include some errors)
I can also figure out how to send an emoticon message through LINE.
I wish I can send some emoticons, which I have to buy to use them, but it doesn't worked with an error message "current user does not have this sticker" :(
ps. you can send some charged emoticons in LOCO protocol for nothing :)
Next : LINE protocol analysis  : session key