This contradicts entirely what you said in your last thread which got closed, amidst the waffle about how you could not get addicted or brain changes could not occur with once weekly use of heroin/Oxycodone and tolerance to Oxycodone could not occur under this once weekly regime, despite the dose having more than doubled, yet here you are, asking how you can withdraw from oxycodone/get subs/methadone.
Addiction is not about what you think it is and free will becomes eroded when the reward centres and motivation area of the brain undergoes significant change with repeated use - this is partially why addiction is classified as a disease. Add in physical dependence as you have found, where users will do anything to avoid withdrawal and the cycle begins. Once you are staving off withdrawal, the psychological and physical changes are underway.
No doc will prescribe you opiates "to taper" and you'll never get any opiates ever again in a medical setting if you go in and admit illicit i.e. non prescribed use and addiction - you need to either go through withdrawal and never touch opiates again, or get a sub or methadone doc. If you think oxys or scag are hard to quit now, wait til you try and quit a long half life opiate.
You can get out now, or trade your soul with the devil.