Quoting fbissey@...:
> First I want to solve the problem of eselect not listing stuff that is
> properly
> installed. In particular gsl and blas-reference are installed 
> properly, so are
> their particular alternatives. Yet "eselect cblas list" and "eselect
> blas list"
> return nothing. I think I have an idea of where the problem is. I just need a
> bit of time to investigate.
>
Found it! In alternatives.bash.in we have:
ALTERNATIVESDIR_ROOTLESS="@sysconfdir@/env.d/alternatives"
ALTERNATIVESDIR="${EROOT}${ALTERNATIVESDIR_ROOTLESS}"

EROOT is basically the prefix path, so the idea is you add
the prefix in the second line. Except that @sysconfigdir@
already include the prefix....
So instead of looking for alternatives in:
/Users/frb15/Desktop/Gentoo/etc/env.d/alternatives
it looked for them in:
/Users/frb15/Desktop/Gentoo/Users/frb15/Desktop/Gentoo/etc/env.d/alternatives

getting rid of one level of prefix in alternatives.bash got
me some working eselect for blas (reference), cblas (gsl) and lapack
(reference).

I'll leave bicatali to make the fix he deems appropriate.

Francois