I'm a SmallEiffel programmer and just thought about adding ruby as a
scripting part to an eiffel compiler.

My question is about the multitasking and GC.
First as far as i heard the threading implementation is done via
Coroutines. Is this right ? 

What conservative GC do you use ? Is it possible that they live aside
the Smalleiffel GC which is none conservative - normally this should
not be a problem (if you can live with the performance penalty) ?
 
Smalleiffel also works with Boehms collector. Is it possible to remove
rubys GCs and use Boehms for both parts ?