Using PowerShell Invoke-RestMethod to POST large b

I'm trying to use the Invoke-RestMethod cmdlet in PowerShell 3 and 4, to upload a large binary file using a REST API's multipart/form-data upload. Here is a working cURL example on how to perform what I want to do in PowerShell:

curl -i -k -H "accept: application/json" -H "content-type: multipart/form-data" -H "accept-language: en-us" -H "auth: tokenid" -F file="@Z:\large_binary_file.bin" -X POST "https://server/rest/uri2"

I would love to see a working example on how to use Invoke-RestMethod to POST a multipart/form-data. I found a blog post from the PowerShell team showing how to use Invoke-RestMethod to upload to OneDrive (aka SkyDrive), but doesn't work well. I'd also like to avoid using System.Net.WebClient if at all possible. I also found another thread here on Stackoverflow, but it really didn't help much.

[System.Net.ServicePointManager]::ServerCertificateValidationCallback = { $true }

$server = "https://server"
uri = "/rest/uri1"
$headers = @{"accept" = "application/json"; "content-type" = "application/json";"accept-language" = "en-us"}
$body = @{"userName" = "administrator"; "password" = "password"}
$method = "POST"

#Get Session ID
$resp = Invoke-RestMethod -Method $method -Headers $headers -Uri ($server+$uri) -body (convertto-json $Body -depth 99)

$sessionID = $resp.sessionID

#Upload file
$uri = "/rest/uri2"
$headers = @{"accept" = "application/json";"content-type" = "multipart/form-data"; "accept-        language" = "en-us"; "auth" = $sessionID}
$medthod = "POST"
$largeFile = "Z:\large_binary_file.bin"

I have tried both ways of using Invoke-RestMethod:

Invoke-RestMethod -Method $method -Headers $headers -Uri ($server+$uri) -InFile $largeFile

$body = "file=$(get-content $updateFile -Enc Byte -raw)"
Invoke-RestMethod -Method $method -Headers $headers -Uri ($server+$uri) -body $body

I know you asked over a year ago and probably solved the problem, but for the sake of other people who may have the same question, I'm leaving my response.

I notice couple of mistakes in your invoke statement. First, you need to use POST keyword instead of string value. Second, make sure that Content-Type is set to multipart/form-data. So this is my revised statement -

$uri = "http://blahblah.com"
$imagePath = "c:/justarandompic.jpg"
$upload= Invoke-RestMethod -Uri $uri -Method Post -InFile $imagePath -ContentType 'multipart/form-data'

You can check the response from the server by checking $upload.