Download the Back to Basics 2011 package.
Now, choose the level you want to play from the list in the downloads section.
Copy the tr4 file into the data/ folder and copy the script.dat and english.dat files into the main trle folder.
Create a setup link for the tomb4.exe and make sure that Volumetric FX are enabled.
Please take note that Back to Basics 2011 is not playable on a Mac.