Il paragrafo 42. della guida di Tex Live (texdoc texlive) dice quanto segue:
4.2 Portable (USB) installations
The -portable installer option (or V command in the text installer or corresponding GUI option) creates a completely self-contained TEX Live installation under a common root and forgoes system integration. You can create such an installation directly on a USB stick, or copy it to a USB stick afterwards.
To run TEX using this portable installation, you need to add the appropriate binary directory to the search path during your terminal session, as usual. On Windows, you can double-click tl-tray-menu at the root of the installation to choose between a few common tasks, as shown in this screenshot:
[omesso screenshot]
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Da quel che capisco serve proprio a fare quello che vuoi tu.
Ci sono anche altre informazioni nella spiegazione dell’opzione -portable nel paragrafo precedente.