There was a tiny linux distro that could run on the 2500 series (uClinux), but otherwise, IOS is a proprietary operating system, and I doubt you will find source code to it anywhere.
uClinux is still out there, I downloaded it maybe a couple of months ago. Still have it on my Mac, if you really want to look at it I can upload it somewhere. It ceased active development a loooong time ago though.
Cisco may license it like Microsoft does for the Windows kernel to very select universities for study purposes, but Ive never heard of it happening.
Your better bet might be to implement something between a series of *nix boxes as a proof of concept, rather than wasting too much time trying to get something running on a Cisco box.
And FWIW, what you are trying to achieve is well beyond the realms of CCNA and will not really help you one bit towards obtaining it. Even CCIE I would imagine. Cisco certs are not about analysing the operation of protocols and technologies to determine how they can be improved, more so just to understand them so you know how they work.
For all its worth, if you think you have something, then as I mentioned above, come up with a proof of concept, write an RFC about it, and publish it and see what happens. If it can be made any better, Im sure there are people out there that want a better routing protocol.