I wonder… could risk live repartitioning, and creating a partition for the bootable install media and another to install to… [0] and manage to jiggle the bios (and/or whatever bootloader) to boot into that partition, same as if booting from dvd or usb, and proceed to install from there… as ever, and especially with a move like live repartitioning, backup everything first. … though, backup to where… if a meagre usb pendrive’s considered too pricey, it seems unlikely there’s adequate backup capacity around. … or maybe just yet to encounter (and thus appreciate) the utility of a (or two) usb pendrive(s)? It has posed an interesting challenge though, once the usb pendrive hand is tied behind our back. And presumably dvd install’s not direct from online enough either. … Virtualbox’s direct from online, without even rebooting… though then that’s just in your virtualbox, nor running direct on metal. … Sorry, rambling broadly about the op question here, instead of specifically replying to that reply.

[0:… Though as I think of that my brain starts shouting “just install gentoo”. No, brain. That’s not what op asked for.]