Had to revisit this problem in my project in the context of some other issue..and finally got it working this time around (for those who might come across a similar issue):
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Content-Disposition: form-data; name="ToDo"
Content-Type: application/json
{"ToDoId":32,"InstructionId":6300460,"Description":"Description","Comment":"Comment","DueDatetime":"2014-02-28T16:44:52.8140079Z","SubmittedDatetime":"2014-02-28T16:44:52.8140079Z","StatusCode":10,"Media":[{"MediaId":0,"MediaDescription":"abc","CreatedDate":"2014-02-28T16:44:52.815008Z","MediaType":"Doc","UrlPath":null},{"MediaId":0,"MediaDescription":"foo","CreatedDate":"2014-02-28T16:44:52.815008Z","MediaType":"Image","UrlPath":null}]}
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Content-Disposition: form-data; name="fieldNameHere"; filename="abc.txt"
Content-Type: text/plain
<@INCLUDE *C:\uploads\abc.txt*@>
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Content-Disposition: form-data; name="fieldNameHere"; filename="Foo.txt"
Content-Type: text/plain
<@INCLUDE *C:\uploads\Foo.txt*@>
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