Just 5 steps to add Xfce to your HP Chromebook (via Crouton)
1. Enable Developer Mode:
Note: wipes your Chromebook.
Start with the Chromebook off
Press hold esc and F3, then press the power button
Control + D
Turn off OS verification by pressing enter
This will then reformat the drive for you (takes about 15 minutes).
Note: Whenever you boot your Chromebook, you’ll see a warning screen.
You’ll need to press Ctrl+D or wait 30 seconds to continue booting.
2. Grab the latest release from goo.gl/fd3zc.
Download it, pop open a shell (Ctrl+Alt+T, type
shell and hit enter).
sudo sh -e ~/Downloads/crouton -t xfce -r raring
4. Enter a user name and password when promoted.
To switch from ChromeOS to Xfce and back use:
Ctrl+Alt+Back and Ctrl+Alt+Forward plus Ctrl+Alt+Refresh
Very detailed walk through and screen shots here: