>fairly easy install however after repeating the process 2
>times, I'm getting 404 error on trying
>http://www.mydomain.com/cgi-bin/fatbomb/fatbomb.cgi/admin/do_login

404 means your are typing in the wrong URL to get to the Fatty admin and setting the permissions doesn't have anything to do with this problem.

You need to double check where you installed FatBomb...Did you rename it? Is the folder fatbomb or fatty? Did you upload all the files directly to your cgi-bin?

Chance are you now have two issues:
1 The URL
2 You've changed permsissions trying to fix #1, so this may create a second error.