Gem spec and C Ruby extension

i’m reading both :
Gemspec Reference http://docs.rubygems.org/read/chapter/20#toc and
DeveloperGuide
http://rubygems.rubyforge.org/wiki/wiki.pl?DeveloperGuide

however i don’t see any example to produce a “binary” gem from a *.c
file.

basically, i make use of a MakeFile (given an extconf.rb) and then
compile (given a compil.rb) to produce a “raliasfile.bundle” which is
the binary linked to the right dependencies over Mac OS X 10.4+.

i want this C ext to be installed in :

/path/to/lib/ruby/vendor_ruby/1.8/powerpc-darwin8.7.0

(as rubycocoa.bundle)

is that the right place ?

where could be a test file (test.rb) installed ?

also i would like to install properly a exaple file (sample.rb) ?