forcing postgresql 7.3 to use crypt passwords

We currently have multiple databases running different versions of
postgresql ranging from version 7.1 to 7.3. When we create users in 7.3
databases, it encrypts their passwords with md5, which is not supported
in 7.1. Is there some way to force postgresql 7.3 to use the old crypt
encryption for passwords when creating users?

Apologies if this message shows up twice. It didn't seem to be going
thru when I sent it without subscribing.

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Kenny Drobnack