Hello Brennan,
No worries, this is never too late
First of all, some remarks concerning the configure options listed in the page you linked:
o
--disable-mpi-io disables (sic) the use of MPI I/O feature when writing/reading restart files (and post-processing files in a near future). It is provided to tackle with some bugs encoutered with some MPI implementations and for NFS systems without file locking. However, we know provided an option to cs_solver executable to control this feature at runtime and no more at configuration stage (--mpi-io with different options: off, eo, ip IIRC);
o
--disable-openmp is the default, no need to provide it to configure script;
o
--enable-gui, ditto;
o only
mpicc wrapper is needed as Fortran files do not include MPI features (but this is a detail...).
There also something wrong in the pre-requisites definition: Metis version can be 4.0.1 or 5.0-pre2, the number 2.3.4 is rather related to MED.
Now, concerning
Code_Saturne ebuilds, I'm far from being a Gentoo expert... sorry! Nonetheless, here are some comments:
o SRC_URI might need some adaptation later on, because 2.0-rc1 version has been posted in this forum because of we currently don't have access to http://www.code-saturne.org to upload the archives. So this might change in a near future;
o MED version is not required to be greater than 2.3.4, we only require MED >= 2.3 IIRC;
o you explicitly set MPI to OpenMPI in FVM ebuild, contrary to the kernel ebuild where it is set to the virtual package
o CXX need not be set, as we don't have any C++ sources in the code;
o I don't think you need to specify --with-bft in MEI ebuild;
o the correct URI for kernel package download is [url]htthttp://code-saturne.org/forum/old_forums_files/569282765/ncs-200rc1.tgz[/url], slightly different from the other packages (because of the different post);
o you set the minimum version to 2.3.5 for MED (ecs ebuild) compared to 2.3.4 (fvm ebuild), this is not coherent

;
o I would advise you to add --with-mei=/usr (or /usr/local, ...) to ncs ebuild for a proper detection of the Python module of MEI (this "bug" has been detected during Debian packaging).
Finally, I cannot say more to your packaging because I don't know much Gentoo ebuilds... Please, let us know whether these ebuilds go in standard Gentoo repositories, so that we can advertise them.
Good work anyway, and thanks for you interest :)
David