and refer you to the post: Rebuild customized backtrack from scratch? in regards to building your own distro. Also note that since the Debian package management system is used on the new and shiny BT4, you're likely to need different repos for some of the stuff included here, to make it work with FC.Code:dpkg --list
If you were planning to create the distro and release it for public use... it's not going to be anything but trouble. Another thing to consider is this: For a distro to be even half-decently usable and bugs to be worked out, etc. you're going to need a dev team. Linux has gotten so big that it'd be a retarded task to commit to building and maintaining a distro all by yourself.
Two Cents (*plink*),