Only problem is a PPC-based Mac is a requirement. However, I would strongly recommend you stick with Apple's Classic mode, as it has much better compatibility, and integrates (almost) seamlessly with OS X. If the System and Applications folders of a non-bootable version of Classic were placed in a disc image and used in a PowerMac emulator, would the image be able to successfully boot OS 9 on the emulator? However, I recall that Mac OS Classic supposedly can be copied entirely to another hard drive by copying the System and Applications folders. Ever since 2003, Apple changed the firmware on their PowerPC machines so that they would no longer be able to boot the included Mac OS 9.2.2 naively.
