Installing ubuntu on an external HD

[Charles Mims]

I have an Apple iBook and an external HD.  I am very familiar with Linux
on the PC.

I am interested in trying Ubuntu, however I would like to install it on
the external HD (firewire).  Can Ubuntu be booted from an external
drive.

The HD is 120G.  I have MacOS X on the the first partition.I have two
free partitions created by the Apple disk utility available for Ubuntu.
I would plan on using one for Ubuntu and one for  swap.  Can I use the
partitions created by Apple or will I need to delete and recreate the
partitions during the install of Ubuntu.  Also where would I install the
bootloader i.e. the internal HD or the external HD; which would not
always be attached.