Modifying HTTP POST data when request made by Ajax in IE11

[slav...@gmail.com]

Hello,
I'm successfully wrapping the POST stgmedData.pstm stream in IInternetBindInfoEx wrapper and modifying the response data.
I'm having an issue with file uploads to SharePoint 2013, Salesforce, Gmail attachment, etc...
Couple of things fail:
First I fail to get the POST mime-type, GetBindString with BINDSTRING_POST_DATA_MIME with hresult 0x800c0012
Then when I try to read from the stream I get the first chuck with E_PENDING, any subsequent read attempts return E_CHANGED_STATE.
When I only monitor the original reads I see a similar behavior and the first chunk is read with E_PENDING, and then next read successfully reads the rest of the file and gets S_OK and S_FALSE...
I can't figure out how I can read such a stream and then
There is some undocumented interface that my wrapper stream gets queried for: {2F68429A-199A-4043-9311-F2FE7C13CCB9}
Hope that you can help me.
Many thanks!
Slava