1. Put all the features and plugins into an .eclipseextension folder (as if actually "installed" on the stick, including unpacking feature jars). Installation is then
Help > Software Updates > Manage Configuration... > Add an Extension Location > (restart when prompted).
Optionally, they could copy that folder to their hard drive and point Manage Config at a local folder rather than at the stick.
2. Put the features & plugins into MULTIPLE .eclipseextension folders (one per functional group) so that people can install chunks (by repeating step 1 above for each folder) rather than the entire whole. Benefit here is a smaller Eclipse install. Detriment is less "full install" cross-project testing by attendees. Smaller memory footprint with less startup plugins loaded. Choices would probably align along the same lines as the EPP bundles. One added wrinkle, too, is that if chunks are installed in the wrong order and user restarts Eclipse in between, things may end up temporarily broken (eg., installing WTP chunk w/o EMF chunk first) until subsequent extension folders are added.
The reason this is arguably "simpler" than making people use a "local update site" is twofold. a) less typing for users (at the expense of more work for whomever is setting up the stick); b) files can simply be copied; Update Manager 'pick-and-choose' process is avoided, and nothing needs to be unpacked / duplicated on disk.
And it introduces people to oft-unheard of art of maintaining installed features via Extension Locations. ;-)