There will need to be a mechanism for choosing a sound card, for example on boxes that have both an HDMI and speaker output. Perhaps there should be an audible tune to let the user know that the boot menu is waiting for a choice. I'm not entirely sure how the menu entry would work, since it has been a while since I've used a Gentoo based system. From what I rememmber, the parameter given to the kernel was speakup.synth=soft. Wiki entries for using espeakup on the installed system should be written. I don't know if there are already Gentoo articles on this anywhere, but I am willing to help out as I gain more experience.