The open Sourcercer has an excellent and very detailed installation guide. It describes what each step does and why it is necessary. Great Job Alan!
Link: How to install OpenERP 7.0 on Ubuntu 12.04 LTS
Pro: Complete control over where and how OpenERP is installed
Con: Not an automated installation
This method can also be used to install version 8.0 Alpha from the trunk directory, however you will also need to include the following required libraries that were not needed in version 7.0
sudo apt-get install python-pypdf
sudo apt-get install python-psutil