I recently had a go at replacing the Liteon 5045 internal DVD drive with a Liteon IHAP122. I had the same problems as some others in having to "modify" the internal steel slot that the drive goes through. This is necessary to get the front of the DVD drive flush with the inside of the plastic front facia.
I found it was fairly simple to remove the front face off the new drive as well as the drawer front. The Liteon 5045 drawer front can slso be unclipped. To reattach this to the new drive you need to make a few incisions to make some "keyways" for the drawer front to locate in place properly.
I also found that I could screw the drive down if I drilled a couple of 5mm holes in either side of the aluminium casing above the location points in the existing case. At these points on the base of the DVD drive there are two circular plastic areas. By drilling a small hole through these I was able to insert some screws and tighten them up by putting the screwdriver through the case.
I re-assembled the case and tried it out and it recorded and played back first time. Unfortunately I forgot that the drive needs to have the region code initialising. I did this using an IDE to USB cable but you can obviously just mount the DVD drive temporarily in a computer first.
Once the computer sees the drive if you try and use it to play something you get a pop up message saying what region do you want to set it to. Once this is done the drive plays back commercial DVD's no problem.
As I have used the region hack on the 5045 I used to be able to play region 1 but I haven't checked that out since replacing the drive.
Dunc
March 2011