I'm definitely not trying to tell you "just don't do it", but we don't generally provide advice on how to prepare stuff like this for injection. There are a lot of other good resources on the internet that will be of use to you, but this is a difficult one for us. Like I said, we are not a "just say no" community, but we draw certain unofficial lines regarding practices that are just completely and inherently unsafe. Injecting pills like the new OP Oxycontins is fraught with danger and potential for serious complications. You can end up with solid particulates in your blood, which can kill you in a variety of painful ways.
The best advice that I can give is, if you do decide to go forward with this process, you absolutely must use descending gauges of Micron filters in the process to ensure that you have removed as much of the harmful stuff as possible from the pill.