Logging usernames/passwords

Hello,

I'm looking at a way to log usernames/passwords in plain text.  The reason
for this is that we are moving away from a local passwd database, and have
no way to copy this DB to the planned format.  If anyone has any better
suggestions, I'm up for it, but i think the best, plainest way would be to
log successful logins(with usernames/passwords before crypt()) and dump the
info into a file on the local machine, which we could then parse and use to
enter data into our new db.  Thanks in advance,

Andre