OS9Helper writes to the Installer to enable installation of 9.2.1 and 9.2.2 on unsupported Macs, be they 60x or G3-upgraded. The code alteration cannot be written to a locked CD, so the upgrades must be installed from the downloaded disk images for 9.2.1 and 9.2.2. The accompanying text with OS9Helper states this requirement quite explicitly. If you still get the quoted message when you use disk images, they are more-than-likely to be corrupt.

de