> Is it possible to run a stored procedure from command line?
>
> I know it's possible with isql and external "command file", but I'd
> prefer to do it with out any external files.

Write simple console application for doing it.

Or use FSQL tool from here
http://www.volny.cz/iprenosil/interbase/fsql.htm

FSQL -do "execute procedure p; commit;"

Ivan