I have started to use R2 and I get an OAuth token and tried to simply pass it in to the REST calls and it seems to work for me. These are internal calls to REST APIs that we have written. I am surprised it worked so easily (just be adding the setrequestheader). I didn't think this was going to be supported until R3. Call me a happy camper :)
For the new RESTClient I simply add a request header with the token and it works
I got OAuth2 working for sending emails via Gmail, but I have to tell you it's somewhat flaky. Don't know whether that's my code or Gmail. So I'm not sure there'd be a value in posting my code (nor, I'm afraid, do I have time right now to separate it out well enough to do so).
Crap, I didn't read the posters name until after I posted my answer. Your Quickbooks access is still not complete. Someone at the conference gave a session on saving files to Azure blob storage and made use of my Bcrypt example.
Check out the OAuthClient object. Best bet is to create a service account (hopefully they have that) and get a client secret code. You use that to get an OAuth2 access token which should probably work the same as your OAuth1 token.