NCommander had a multi-part stream of building LFS up to Firefox. He's gotten up to building Xorg and the Firefox prereqs so far. I don't know when he plans on doing the final push to building Firefox.
Part 1: https://www.youtube.com/watch?v=tCh0XjyIAKU
Part 2: https://www.youtube.com/watch?v=egzyIFsQ3Nw
He also managed to dig up a copy of the proto LiveCD of Yggdrasil Linux and get it working.
If you want a gentler slope, maybe something like (in this order, and keep doing stuff on a "earlier level" on the list):
1) Install packages via your packagemanager from the cli and other sysadm tasks
2) Change settings for stuff by files and not by gui
3) Install things not packaged by your package manager
4) Try arch (no compiling but a lot of setup)
5) Try gentoo (lots of setup and lots of compiling)
6) Try LFS in a VM (NEVER on a system, that you actually need)