How to use functions/variables in DBLinq.MySQL

This is my query:

SELECT IF(@@old_passwords, Old_Password(?), Password(?))=`password` AS pass
FROM mysql.user WHERE User=?

Can I translate this to Linq, or do I have to just开发者_如何学编程 extract the connection from the data context and do it the old way? All the documentation I can find is about simple queries: selects; joins; aggregates.