I just happen to have bought an external 5.25" IDE enclosure (mostly for external hard drives, but it was cheaper than a 3.5") and have a dvd drive that the Efika happens to detect and lists under the `devalias` command. Can I use this as a way to install Ubuntu, Gentoo or any other OS a bit easier? What is the actual proceedure for doing so - do I just use the standard PPC ISO, etc?

you can use your dvd drive to install linux on your Efika, but not using the regular PPC Cds you may find. It still needs an installer or kernel suitable for the Efika. You can still burn the installers provided on this forum or at www.efika.info on a CD then launch it, but is it easier than using a usb stick ?

Probably not. I had hoped this lucky find might lead to making Ubuntu or something easier to install... I have no clue where to start with that one.
Oh well.