These are the directions from the original post
"Download Ubuntu 13.04 image from here. Put the image in the memory of N7 or to USB flash drive and go to recovery. Select Advanced -> MultiROM -> Add ROM and choose "Ubuntu" as ROM type. Then select the Ubuntu's image and confirm. Clean installation of Ubuntu is 1.5gb big, and takes a while (10 minutes?) to install."
The only selections that I have to choose from is: Android, MultiROM installer (*.mrom files) and Ubuntu Touch.
This is the original post