Use find to search for modified files:
find / \( -perm -004000 -o -perm -002000 \) -type f -ls
a good site to goto for alot of hacks etc.. is neworder. don't get carried away with all the scripts there though. Some are quite dangerous in the wild
and everything there should be run on closed networks before you get used to their purpose.
http://neworder.box.sk/