From the manual (http://lorebook.lotro.com/wiki/LOTRO_under_Linux_and_Mac_OS/X)
It's time to get working on getting LOTRO to run on OSX! First thing you want to do is create a new bottle, and call it LOTRO.
Important: There have been reports of problems if the bottle name contains spaces, so please keep it to one word, no spaces.
Select Windows 2000 for the version. To do this click on "Manage Bottles" and choose the + sign to add a new one (I made this one my default bottle).
MOM/Leopard note: skip FakeNET11 instruction, go to step 2.
1- Once this is complete, choose the "run" command from the "Programs" drop down menu.
Type in "regedit," and a Windows looking regedit prompt should come up in X11.
Select Import from the regedit menu and navigate to the FakeNET11.reg that should be on your desktop. You will not get a successful registry merge notice like you would on Windows, but the settings should be added as long as you selected the .reg file. (Note that you can do this step manually if you so prefer, just open the .reg with a text editor and make the registry changes outlined in the file manually via the regedit menu.)
Also, the suffix to the file doesn't really matter (you can always change it), but make sure by opening it in a text editor the file contains only registry information, and not <html> stuff