I am trying to connect to my evohome system ahead of developing a way to hook up my homeseer SEL linux controller. I am trying an http POST to "https://tccna.honeywell.com/WebAPI/api/Session" and am passing username, password and applicationid as headers. I get back the following:

[
{
"code": "ParameterIsMissing",
"message": "'request' is required."
}
]

I have tried using a couple of API tools but no luck - any ideas???