The EZ HOST device can be configured using LCP commands over HPI. This is the co processor mode in which the EZ HOST can function where it communicates with an external processor over the HPI or SPI or HSS interfaces. The BIOS User's Manual will provide additional information on using these commands. This document has been attached in this article for quick reference but is also available in the documentation of the CY3663 dev kit.
As for the development system, having the development system is not really required. However downloading the CY3663 development kit will provide you with a known good working environment to build and test your application with.