My reply is based off of my technical readings of the collateral for the e6xx processor and associated chipset.
I think Intel recommends use of the IOH but the LPC interface does support use of a flash.
If you go look at ADI Engineering (http://www.adiengineering.com), they have done precisely that. THey have a "Thin E6xx board that has a single chip solution (no IOH) with just the e6xx processor + LPC NAND flash that contains the bootable image. They use a CPLD that bridges between LPC and NAND and acts as a controller.
hope that helps,
Ramakrishna saripalli (Intel corporation)