Not too sure about the sub... But if you seriously want to get off the oxy my best advice is to cold turkey. I know many people will flame me for this. I was on 180mg/day of Oxy IR and 120mg/day of extended release for over a year and a half. And I cold turkied it. If I can do it, you can too. Talk to your doc about it. The worst of it is the first week when you are WDing, it is hell. After that it is mostly high anxiety and... well, the runs. Your doc can prescribe you Clonazepam for day and Valium for night (or really bad panic/anxiety during the day), and a good sleeping pill to get through it...
I really wish you the best of luck and feel free to ask more questions if you have any!