Xastir Setup (This information is based on my Linux Ubuntu 9.04 installation with Xastir 1.9.4 installed)
First of all you need to download and install Xastir.
Since the otwincfg.exe is a Windows application you have to download Wine, this will allow you to run Windows applications within Ubuntu.
To get Wine installed type the following at terminal prompt: sudo apt-get install wine
Then you can download the otwincfg.exe program and to make it easy, save it on the desktop.
To start otwincfg.exe you have to right-click on the program and select Open with "Wine......."
So, back to Xastir, assuming you have installed the application press Interface and then Interface Control, then click the Add button, select Serial KISS TNC from the list and then the Add button.
Depending on what you want there are some options there to turn on and off but you have to specify the comport for the TNC.
Typically Com1 is /dev/ttyS0
Port Settings 9600bps
Hope this info is usefull, I have been using Xastir with my T2 for over a year now as a Fill-In digi with IGate TX/RX (LA5PPA-2)