PASSWORD() function for postgresql?

I am looking for a postgresql PASSWORD() function that
produces hashes compatible with MySQL's implementation.

I am converting from MySQL and I know of no other way to
use the passwords I have in the old database other than
having a compatible PASSWORD() function.

I have searched around for one quite a bit but could not find
one. Does anyone know if someone has written something
to do this already? If so, where I can get it from?

I am off the list so please include me in CC, etc.

Thanks in advance,
Jason DiCioccio