Modifying FTP server for site to site (FXP) transfers

I'm trying to modify an internal FTP server to allow server to server (FXP) transfers between another internal server.

I believe the problem is related to the IP address of the connection is different than the clients IP address.

One of the error messages I receive is:

425 Possible PASV port theft, cannot open connection.

One solution I've found in my searches is to run the disable-pasvip switch when compiling WU-FTPD. I'm using the FTP server that comes with Snow Leopard Server software, which I believe is based on WU-FTPD.

Are there any other solutions out there for configuring the FTP server to accept a site to site transfer without recompiling the Snow Leopard FTP server?