This howto was taken from the Scooter Web site posted by Chris. I have it here purely for my own convenience.
Install 32-bit compatibility libraries
sudo apt-get install ia32-libs lib32asound2 libasound2-plugins
Install 32-bit version of QT3. Download the 32-bit .deb package for QT3 from the Ubuntu page list site http://packages.ubuntu.com/, remember to follow the link for your Ubuntu version. (Hardy, Jaunty & Lucid work).
Extract the contents of the .deb package.
dpkg-deb --extract libqt3-mt_VERSIONubuntu3_i386.deb libqt3-mt
Copy the QT3 libraries to Kubuntu's folder for 32-bit libraries.
sudo cp -R libqt3-mt/usr/lib/* /usr/lib32
Install Beyond Compare 3 for Linux deb package.
sudo dpkg -i --force-architecture BCompareLinux_080814.deb
There will be some errors but ignore those
dpkg: warning: overriding problem because --force enabled:
package architecture (i386) does not match system (amd64)
Selecting previously deselected package bcompare.
(Reading database ... 149526 files and directories currently installed.)
Unpacking bcompare (from BCompareLinux-3.1.3.10374_i386.deb) ...
dpkg: dependency problems prevent configuration of bcompare:
bcompare depends on libqt3-mt (>= 3.3); however:
Package libqt3-mt is not installed.
dpkg: error processing bcompare (--install):
dependency problems - leaving unconfigured
Processing triggers for desktop-file-utils ...
Run Beyond Compare by typing "bcompare" in a terminal.