I tried to do this, but i do not think it is possible (i could be wrong).  
Regasm registers with the com categories and points the inprocserver32 to the
mscoree.dll so that the .net framework can put a wrapper around your class so
that com can talk to it.  This wrapper will handle all the hard stuff for you
(such as the classfactory).  

I could not find a way to get this to work since i too was using an
outofproc server (localserver32), so i had to maually create the registry
entries for the com category, then implement the class factory in my code as
well as some other details.  

There MAY be a way to use the .net com callable wrapper with an outofproc
server (exe) but i have not found out how.