The rear wheel bearings are pressed in on the E46. Your going to need a few tools like a slide hammer to remove the hub, a bearing seperator to get the inner race off of the hub, and a bearing press to press the new bearing in.
An air hammer will make it a whole lot easier to remove the rear axle as well. They usually get seized in there and hitting it with a punch like in the instructions below just wont work.
Here is a link to the replace the rear wheel bearing in the E46 3 series.
Let me know if you need anymore help.
If you found this answer to be helpful, please press Accept. You can always reply after accepting an answer if you have more questions or need further assistance.
Positive feedback is also appreciated. Thanks for using justanswer.com