Syncronization with transformation
Use a linked server as Aaron mentioned and bulk load your data to your SQL 2000 tables after doing the transformation within SQL 2012. You could just create a few staging tables in SQL 2012 where you can place your transformed data as it comes in.

Beware of linked server from 2012 to 2000 using SQLNCLI10: see here
SQLNCLI10

The new client SQLNCLI11 does not work with SQL 2000 as far as I know.