Customising files in a beta is a bad idea.
But, actually, yes it is possible to find out what files have changed.
1) Find out the revision number of b5
2) Deduct 1 from that number.
3) Visit
http://mirror1.cvsdude.com/trac/rethrash/tattoo/log/tattoo/trunk
4) In the box to the right of "and back to", type the number.
5) Press ’Update’
6) Make sure the top Rev has the right radio button checked
7) Make sure the bottom Rev has the left radio button checked
8) Press ’View Changes’
This will then list all the files that have had changes - and show you what changes were made, which will be handy if any of the files you’ve edited have changed.