Eat them.
They only contain 5mgs of oxycodone. First of all, if you've been shooting enough smack to get physical withdrawals, at bare minimum you would probably need at least 20mgs of oxycodone via IV to really get off.
The pills contain acetaminophen, which is REALLY BAD to inject.
Then you have the fact that the pills weigh over 500mgs a piece. You'd have enough trouble trying to get all that into a 1CC needle and imagine all the oxycodone that would be wasted as you're trying to suck up the water through the cotton as the cotton gets plugged with all the APAP and filler.
It just wouldn't work. At most you might pull up 1-2mgs of oxycodone from an Endocet.
Endocets are EXCELLENT for coming off dope, though. And the fact that you CAN'T shoot them actually works in your favor. Why? Because if you have a large enough supply, you can take these for a few days to stave off withdrawals and it gets you out of the habit of using a needle, so it makes it a lot easier to quit. I would suggest taking about 4-6 at a time (20-30mgs of oxycodone) orally. Try to use them sparingly and ONLY take them when you absolutely can't stand the withdrawals anymore. That way they'll last you longer and be more suitable for getting off the smack.