Set authProfile values in code

Looking for how I can set the access token for OAuth2 programmatically.  For untold reasons I need to get the access token seperately.  I have external code to do that and can expose separately but it's only helpful if I can set the value in the authprofile in an automated fashion.  Ready API implementation does not work for me. I'm sure it follows the standards but does not work for the instance I am dealing with.