I've been playing on Windows and thought I would install in Ubuntu linux. First, I installed from their software center and it was able to get original pak and I later installed pak.britan. I didn't like them and wanted pak.comic but I couldn't figure out where the pak files were being stored. I uninstalled everything and did it manually. Here is what I did:
 Download file
[A] Go to http://www.simutrans.com/en/download
[B] Select the link to download from the Sourceforge repository
[i] Save the file somewhere, e.g., /Downloads
[C] There is no specific download for linux.
 Extract the install file
[A] Extract into your /home directory
[i] You will get a directory named /simutrans
 Install the graphics pkg
[A] To install the pakset, go into /simutrans
[B] Run the script get_pak.sh
[i] You will get options to select the pak file and then install it
 Run simutrans
[A] Double-click the executable in /simutrans
This is much simpler than anything I could find in google search. I hope this is the right sub-forum.