I retested Trillian v184.108.40.206 (MD5: 69d7a248b35a292c10c3d1ecdeed77bc).
I advise you to install it using Sandboxie and outside the Program Files directory, because the installer leaves kind' of a mess on the system.
All the needed files are in the installation folder.
I edited the .ini according to the instructions from the database entry.
The results: well...settings are saved in the installation folder, but there are so many bits and pieces left all over the place, that it's not even funny. Not essential pieces, though.
If you really like this app, use it. I do! I use a JPE launcher for it, though.
Not stealth! Actually it is the "least stealth" portable app I know!