API - Sample Add Attachment via Powershell?

I'm very new to Invoke-RestMethod and have been successful at pulling the data that I want.   Thanks to a few posts I've seen here. 

But

One challenge that seems to stump me is how to add an attachment to an incident via powershell.  I see the api docs have a curl example.  I have not seen any PS examples and my poor brain is unable to convert the syntax of curl to Invoke-RestMethod.