I'm not sure if OS X sort of ear-marks certain kexts during install for potentially faster loading or something. Dunno.
If you're using an SDR RAM eMac, then the architectures should be similar enough that everything should've been virtually identical... except perhaps the audio codec. According to Apple's Developer Notes, on the PMG4 DA, the audio codec is called "Tumbler" and is connected to the UniNorth by only the I2S bus, whereas eMacs use an unnamed codec that uses both the I2S and I2C buses.
The DA's audio subsystem is more capable than that used in any eMac, to be sure, so perhaps there are some extra kexts used on that one, or a modified kext or something.
As for it not wanting to use a replacement kext, maybe try putting it in FW TDM to another machine or something instead of booting it.
Sorry I can't be more help. I'm more of a hardware guy, really, and OS X still beguiles me when I venture into the deep, dark UNIX catacombs lying beneath that tranquil Aqua façade.
If you're using an SDR RAM eMac, then the architectures should be similar enough that everything should've been virtually identical... except perhaps the audio codec. According to Apple's Developer Notes, on the PMG4 DA, the audio codec is called "Tumbler" and is connected to the UniNorth by only the I2S bus, whereas eMacs use an unnamed codec that uses both the I2S and I2C buses.
The DA's audio subsystem is more capable than that used in any eMac, to be sure, so perhaps there are some extra kexts used on that one, or a modified kext or something.
As for it not wanting to use a replacement kext, maybe try putting it in FW TDM to another machine or something instead of booting it.
Sorry I can't be more help. I'm more of a hardware guy, really, and OS X still beguiles me when I venture into the deep, dark UNIX catacombs lying beneath that tranquil Aqua façade.