I found that post in geonet as well. I've tried appending the token to the url as suggested by Bjorn, but that did not add the Authorization http header that I need. I've also tried using the IdentityManager but couldn't get that to add the token in the way I need it added, either.
In some JS frameworks, you can set up default http headers that are added to every http request made through that framework's http client. I just haven't found a way yet to do that with the ESRI/dojo JS api.