Hi.

The empeg kernel already uses an initrd (that is loaded from flash). Don't know how good the kernel would handle a stack of initrds.

The other way would be to patch the kernel to boot from /dev/hda2, and install a new root filesystem there that contains the preinit and mounts the original root filesystem to run the player/original init. The tools to do this are readily available. You can even create a custom .upgrade file to initialize the hda2 partition, install the patched kernel and that could even do a multi-staged install IIRC, installing a "small" hda2 image first, which installs a userland app on the music partition and a "full" hda2 image next which install the preinit and a multitude of tools on the hda2 partition.

cu,
sven