Tip: Where to install

[ScratchMonkey]

When installing, select a new directory in /tmp. Name it after the 
version/build. Then tar up this directory and unpack it where you really 
want it, and untar a second copy next to it in an "archive" directory. Make 
the latter copy read-only ("chmod -R a-r .") so you don't accidentally 
change any of the archive copy's files. Now create a symlink that points to 
the first copy you unpacked called "current": "ln -s bf2-1.1.2475 current". 
To switch versions, you just change the symlink. To figure out what changed 
from the "pristine factory files", just diff your working copy against the 
one you put in your archive directory ("diff -r current 
archive/bf2-1.1.2475").