The registration code is part of the manifolds project (of Cindy Grimm, Hughes Hoppe et al descent). The manifolds project started out under /map/gfx2/users/cmg/manifolds/
A few years back, when gfx2 went
away, tstaff moved the project to /map/gfx0/users/gem/manifolds/ and
that's where it currently resides, as far as I know. A more
appropriate place would have been /map/gfx0/projects/manifolds/.
With respect to the manifolds project, I have no special privileges. The project used to belong to the 'manifolds' group, but when gfx2 went away, it became 'graphics'.
The reason the manifolds project is not under $G, but separately on /map/gfx0/, is, if you remember, because the manifolds project comes with its own make, bin, lib, include etc architecture. When $G showed up, we did discuss the possibility of integrating the manifolds project with $G. Integrating the two is by no means trivial (moving the manifolds under $G is more or less equivalent to moving all of $G under the manifolds project). At the time, we agreed to let the manifolds project be, as long as it was on /map/gfx0/.
Applications built on top of the manifolds project go into
[...]/manifolds/src/programs/.
The registration code (HackSegmentation) is one such application.
Make rules are under [..]/manifolds/make/.
Executables go to [..]/manifolds/bin/.
Everything grant-related that is not based on the manifolds project, is under $G.
For each application, the manifold-project make rules apply. 'make' in an application directory normally builds the application. The executable gets written to [...]/manifolds/bin/linuxR/ (respectively solarisR, or winR, depending on the platform you're on; R stands for release version, G stands for debug version).
There are a couple of environment variables one needs to set before building manifolds project-based applications. Inside [...]/manifolds/src/programs/HackSegmentation there's a copy of the 'envvars' file spelling out these environment variables. Other than that, the only thing that's not there but is the default in my home settings is probably ARCH = linux.