You can refer following Metalink docs :
Import : 1023811.6
Export : 1015589.6


The attached scripts are meant to pretty much automate what I was doing -- which was exporting from a UNIX database and simultaneously importing to a UNIX database.  You will have to edit to get rid of functions you don't use, like getpassword and oraenvnew.  

Once the pipes are made, Note the naming convention (DB in name), one really only has to change the DB at the top.  Some explantion is at the top.  Remember your permissions for remote shell, ksh, and sh.   Note that destination_dir used by the rsh command is on the destination server, so... theorically you are exporting to a pipe as your dmp file, and cat rsh that pipe to one on the destination, and importing on the destination.  I believe you need to start the import first and it will wait until it gets some data from the export.  If you go the other way around it either doesn't work or your pipe fills up causing you to run out of space anyway.

I think these scripts work together but they are kept for reference only.  Make your pipes first.  If you have questions let me know.

You can always test most of these lines by hand first, and of course hard code some values.  Not sure how you can use this concept with NT.