How to make SELinux file context permanent?

Mon Apr 3 21:30:31 UTC 2006

I have two packages, gcl and ecl, lisp compilers, that
need a context change of some binaries from
  system_u:object_r:lib_t
to
  system_u:object_r:textrel_shlib_t
These files reside in subdirectories of /usr/lib. Is it
possible to set context during RPM creation?
In any case, the changes are not permament, because after
a relabeling (or restorecon) of the filesystem, the context
reverts to the default.
What is the least painless way to do this correctly?
-- 
Gérard Milmeister
Langackerstrasse 49
CH-8057 Zürich