Suppress checking of chmod 700 on data-dir?

Hi postgresql-listmembers,
for a backup-scenario I need to have access to the pgdata-directory as a
different shell-user, but postgresqul refuses to start if chmod is not
700 on the directory.

Is there a way to prevent postgres to check the data-dirs chmod 700 on
startup (and while running) ?

Thanks for your short replies. I could not figure it out in the
documentation.

Regards Johannes
postgresql 8.2.4 on ubuntu dapper
(if this question came 100times, I apologize for being unable to find it)