Master Slave Databases

[eluser]Unknown[/eluser]
I have done extensive research regarding below with no luck:
How do you make CI database session write to master mysql server and read from multiple slave mysql servers?
Now the question boils down to:
How to extend CI database class write to master mysql server and read from multiple slave mysql servers without having to define each databases as $DB1 and $DB2?

I use Doctrine ORM that can be easily extended to use master and slave servers. If CI database can be used with Doctrine ORM, that's even better.

Any solution/suggestions would be greatly appreciated!

[eluser]danmontgomery[/eluser]
http://www.phpandstuff.com/articles/code...-and-setup