Since "Debian Etch" has been superseded by Debian Lenny, I wonder if it is possible just to upgrade Bind 9.4.1-P1-1 package already installed on an Etch box, to a more recent therefore secure version?
All support for Etch ended a year after Lenny was released. Squeeze has also already been released so support for Lenny now has a fixed end date. If you want to run newer versions of services you really should just upgrade to a newer version of Debian that is still being supported by the Debian Security Team.
Otherwise your only other real option is to compile from source.