Pressing and holding the eject button for 3 seconds is supposed to enable 52x reading, but I'm not sure when you are supposed to do it. After you have loaded the disc, I presume. Can someone who owns the drive report the exact procedure?
As for writing at higher speeds, I don't think you can override the write-speed control on that drive, so the only way to get higher speeds is to put in media that the drive likes. What media are you using right now?
The setting burninfool was referring to is the buffer underrun protection (see the check-box in the lower left corner):
I'm not sure if disabling buffer underrun protection will also disable the automatic write-speed control. I don't think it does, but even it does, you really don't want to do this. As burninfool said, it can lead to errors. Specifically, it can result in unreadable coasters. So, it is better to try another brand of media if you want to get 52x burns.