I've looked into Corsis on Ubuntu and so far it is not very promising, at least on my machine. The issue seems to be that the Corsis (nee Tenka Text) that you download from Sourceforge requires Mono version 2.2, while the default version installed on Ubuntu 8.10 is 1.9.something. When I try to run it on my machine, it blows up with a bunch of errors.
I've perused this site as well as Googling around and I get the impression that there are all kind of issues with version 2.2, which is why the people who make the packages for Debian (and therefore Ubuntu) have not made a package. Normally when you run into this issue, it is pretty easy to just go and grab the source code yourself and compile it on your machine. Unfortunately Mono is a very large group of software and it isn't quite that easy (which is why the Debian guys don't just compile it up and package it).
I don't use Mono so I can't really speculate what the issue is on my machine. I am running a 64-bit kernel, which sometimes adds some subtle problems with this kind of thing, so you might have better/different experience trying to run it.
If you want to try, it is pretty easy to do. You should have Mono installed by default, and you said you have Tenka Text on your desktop. As per the instructions on the Sourceforge site, you just need to open a terminal, change to the directory that has the program, and run the command to run the program. To do this: [INDENT]On your desktop to go *Applications -> Accessories -> Terminal*[/INDENT] This will put you on a command line in your home folder. You change to your Desktop folder/directory by
cd Desktop
You can then change to your Tenka Text directory by
cd TENKA-TEXT-0.1.3.4
or you can do the above two in one step with the command
cd Desktop/TENKA-TEXT-0.1.3.4
From here all you are supposed to need to do is type
mono Tenka.Text.WindowsInterface.exe
and it should run. This is where I get a whole slew of errors and it doesn't run.
If it does run, let me know and I can show you how to make this a click-an-icon type of thing to get it to run so you don't have to go through the above steps every time you want to run it. This is also true with the Antconc program, by the way.
If this doesn't work for you, there are a few other potential options, but they are much more involved (such as running a virtual machine that boots up a version of linux or Windows that does have Mono 2.2 support). Otherwise, you might have to wait for a Debian/Ubuntu Mono 2.2 package to be put together.
(By the way, this goes to something you posted earlier regarding where things download, but by default Firefox downloads things to your desktop. This is convenient, but can really clutter things up after a while. You can have Firefox ask you where to download things by going to Edit->Preferences->Main and checking the box "Always ask me where to save files" I usually make myself a downloads folder in my home directory and I end up putting all my downloads there.)