The prerequisites for installing IE in Linux is wine and cabextract. To install these 2 packages in Ubuntu, simply run the following command;

$ sudo apt-get install wine cabextract

Next is to download and run the installer script provided by the nice guys at the IEs4Linux project;

$ wget http://www.tatanka.com.br/ies4linux/downloads/ies4linux-latest.tar.gz
$ tar xf ies4linux-latest.tar.gz
$ ies4linux-*/ies4linux

The installer will then download and install the neccessary files and programs after clicking the Ok button at the following screen;

In the end, just execute the following command to run the installed Internet Explorer version of choice;

$ ~/bin/ie6