>Is there something special i must use as command line parameter
>of configure / make ? E.g. a path to include / libs ?
>What is the file / directory structure of OpenSSL needed by ruby ?

I'm not 100% sure about this (can't verify from where I'm at), but IIRC
when compiling Ruby from scratch it will check for the availability of OpenSSL
headers in the standard locations.
If that somehow fails in your case, you could try to build the extension
after you compiled your Ruby w/o it.

Navigate to the ext/openssl directory of your Ruby sources. Run

ruby extconf.rb --with-openssl-dir=/path/to/openssl

Where "path/to/openssl/" is the directory where OpenSSL was installed.
It's the right one if it contains a "lib" and an "include" directory.

If successful, this will generate a Makefile for you. Run

make && make install

and it should now build the OpenSSL extension and deploy it.

Regards,
Martin

PS: Just found this, might help: http://www.ruby-forum.com/topic/90083