Look up linux from scratch. (LFS) is a free online book on how to compile and build your own distro from source code. No respins there.
http://www.linuxfromscratch.org/
Also, the Debian Live project has a book worth reading, though to make a proper respin with a lot of customizations it's more trial and error.
http://live.debian.net/
Another way that is really popular is starting with whatever distro you like and customizing how you like. Then your can copy over any configs needed in /home/username by copying the settings to /etc/skel.
From there you can use a respin tool like remastersys(for debian) to do the work for you. Problems with this is it leaves you with almost no options to tweak the installer, and customizing the live disc in certain areas is impossible. It's also really hard to use custom kernels with these kinds of tools, a lot of the times the tool is only programmed to work with the generic kernels installed, which is a problem I've run into before.
Hopefully that will at least get you started. :good:
If you have more questions, you know how to contact me.