ChessGUI is fully portable since version 0.155.

http://www.hugedrive.com/published/WG/show.php?q=QklHTElPTg==-2e56594a

This means the GUI can be used directly from a memory stick.
To do so, install only portable engines and tick "Portable engine" for each.
For each tournament, tick "Portable GUI" in GUI Preferences.

Portable engines are engines that don't depend on fixed paths (defined in ini
files) to work. Almost all UCI engines are portable. Many WB engines are
portable.

On the ChessGUI website, there is a ready-to-use portable package
(ChessGUI4Stick). It is left to anybody to expand it with better books, more
tablebase files and stronger engines. The package contains a running
tournament that can be continued immediately after unzipping to stick or hard
drive.

On hard driver, use any folder that is not very deep, to avoid too long paths.
If used from stick, limiting the number of debug files (in GUI Preferences) is
recommended.

Matthias.