Cannot switch to any slot. # eselect php list cli readlink: illegal option -- e usage: readlink [-fn] [file ...] [1] php5.4 #
eselect modules shouldn't call "readlink" directly. There are path manipulation functions like canonicalise() available, exactly for the purpose of avoiding such portability issues: <http://www.gentoo.org/proj/en/eselect/dev-guide.xml#path-manipulation> Reassigning to package maintainers.
We have a proposed fix over in bug #552156 but I'm not a BSD user. Can you please give that patch a try and let us know if it works?
I believe this has been fixed and an ~arch version is in the tree (unmasked). If you still have problems, don't hesitate to reopen this bug!