Installing Ubuntu via Boot Camp on 1st gen Macbook running Lion
Boot Camp steps

Download Windows drivers for your Mac.
Partition your hard drive to make space for Windows.
Sets your Mac to default boot into Windows after installation.

None of these options will help you  with your Ubuntu installation except for the partitioning. But this can also be done using Disk Utility. Therefore, I recommend using Disk Utility to change your partition scheme. This will also take care moving your Recovery HD partition (which GParted on the LiveCD will not do that easily).
Easiest Ubuntu Install

Using Disk Utility, add a second &quot;partition&quot; and make that free space.
During the Ubuntu installation process choose to install Ubuntu next to the Mac OS. This will also automatically partition the free space for your needs.
Install rEFIt to sync the partition tables.

Further options

creating a file exchange partition for Ubuntu and MacOSX
manually formatting the free space using the LiveCD in order to create a separate /home directory